Wall Function Research Articles

Numerical PMM test in shallow water using CFD method

This study aims to the estimation of the ship manoeuvrability in shallow water by using the numerical PMM approach, which analyses the hull hydrodynamic responses and manoeuvring performance from the viewpoint of coefficients. The test model is a scaled KVLCC2 tanker operating at a low Froude number of 0.0514. Static drift test and pure yaw test are considered, and the water depths vary from deep water to very shallow water of 20% under-keel clearance. The numerical tank is built based on an OpenFOAM+ package. The free surface is modelled by volume-of-fraction method, and the k-ω SST model associating with wall functions is applied for turbulence. After the convergence tests and validation works, the numerical tank is employed to investigate the wave-depth effect on hydrodynamic forces and manoeuvring coefficients. The present results show that the forces of static drift test, particularly sway force, can be significantly changed as the water depth decreases.

Abdominal wall hernia repair: from prosthetic meshes to smart materials.

Hernia reconstruction is one of the most frequently practiced surgical procedures worldwide. Plastic surgery plays a pivotal role in reestablishing desired abdominal wall structure and function without the drawbacks traditionally associated with general surgery as excessive tension, postoperative pain, poor repair outcomes, and frequent recurrence. Surgical meshes have been the preferential choice for abdominal wall hernia repair to achieve the physical integrity and equivalent components of musculofascial layers. Despite the relevant progress in recent years, there are still unsolved challenges in surgical mesh design and complication settlement. This review provides a systemic summary of the hernia surgical mesh development deeply related to abdominal wall hernia pathology and classification. Commercial meshes, the first-generation prosthetic materials, and the most commonly used repair materials in the clinic are described in detail, addressing constrain side effects and rational strategies to establish characteristics of ideal hernia repair meshes. The engineered prosthetics are defined as a transit to the biomimetic smart hernia repair scaffolds with specific advantages and disadvantages, including hydrogel scaffolds, electrospinning membranes, and three-dimensional patches. Lastly, this review critically outlines the future research direction for successful hernia repair solutions by combing state-of-the-art techniques and materials.

An Evaluation of Inflow Profiles for CFD Modeling of Neutral ABL and Turbulent Airflow over a Hill Model

The implementation of the wind turbine is a major issue in the wind engineering sector. However, the presence of wind turbines in the lower part of the atmospheric boundary layer (ABL) requires an appropriate study for the simulation of turbulent airflow in the wind farm situated on hilly terrain. The use of precise Computational Fluid Dynamics (CFD) simulations for the ABL flow is vital for numerous applications, such as wind energy, building, urban planning, etc. To achieve accurate results, it is imperative that the inlet boundary conditions produce vertical profiles that keep a uniform horizontal distribution (with no streamwise gradients) in the upstream region of the computational domain for all important parameters. A development approach is proposed herein, focused on the imposition of two different inlet profiles when used in combination with the rough z0-type scalable wall function. The horizontal homogeneity of these profiles has been verified by 2D Reynolds averaged Navier-Stokes (RANS) through the examination of a neutral ABL in an empty computational domain using the k-ε turbulence model. The findings indicate that the use of this modeling approach can yield relatively consistent homogeneity of neutral ABL for both inlet boundary conditions. Subsequently, sensitivity analyses were performed on the inflow profiles to forecast the evolution of the bottom half of an idealized truly-neutral ABL and to accurately capture the complex dynamics of atmospheric flows over hilly terrain. This study compares the results with the CRIACIV (Inter-University Research Centre on Building Aerodynamics and Wind Engineering) boundary layer wind tunnel experimental data, showing that the inflow profiles and the presence of topographic complex have a significant impact on air velocity, turbulent kinetic energy and turbulence intensity in the x-direction. The results obtained are in good correlation with published experimental data in the presence of the hill surface.

Double-skin façade simulation with computational fluid dynamics: A review of simulation trends, validation methods and research gaps

Dynamic simulation of a double-skin façade (DSF) with computational fluid dynamics (CFD) can be challenging due to the lack of validated models and benchmarking datasets. Furthermore, there is a lack of consensus in the scientific community on what constitutes a successfully validated DSF model. The present review study identifies simulation trends and research gaps for DSFs simulated with CFD. Additionally, this article presents a series of CFD simulations in which key aspects of the DSF modelling are varied: 2D or 3D modelling approaches, turbulence viscosity models (TVMs), radiation models, and wall function. These simulation results are compared to the empirical data (both temperature and velocity fields) of a benchmark test with laboratory-controlled boundary conditions. This analysis shows that using the k-ε RNG model with enhanced wall treatment and surface-to-surface (S2S) radiation model yields the best results for the 2D case of natural convection flow. Moreover, it is shown that accounting for the velocity field in the validation process is essential to ensure the suitability of a model. Finally, the authors advocate for the use of selected dimensionless numbers to improve the comparability of the different DSF scientific studies. This would also help to identify relevant experimental datasets for validation and suitable CFD simulation settings for specific DSF cases.

Numerical study on wind pressure characteristics of Chinese yurt building under downburst wind

SummaryInner Mongolia is a high‐frequency thunderstorm region in China, and the downburst caused by the thunderstorm weather is a severe threat to buildings. In order to study the influence of downburst on the wind pressure characteristics of the yurt building, the wind field model of the yurt building under downburst is established based on the computational fluid dynamics method, and the effect of the wall treatment method and turbulence model on the numerical simulation of wind pressure of the yurt building under downburst is analyzed. The results demonstrate that the maximum positive pressure at the windward side of the yurt building occurs at 3/4 of the yurt building height under downburst, and the maximum negative pressure at the roof of the yurt building appears at the center of the roof. Compared with the experimental results, the Shear Stress Transport (SST) k‐ω model is suitable for simulating both sides of the yurt building, while the Reynolds Stress equation Model (RSM) is suitable for simulating the windward side, roof, and leeward of the yurt building. The enhanced wall treatment is appropriate for simulating the remaining sides of the yurt building while the standard wall function is appropriate for simulating both sides of the building.

The Contribution of Vascular Proteoglycans to Atherothrombosis: Clinical Implications.

The vascular extracellular matrix (ECM) produced by endothelial and smooth muscle cells is composed of collagens and glycoproteins and plays an integral role in regulating the structure and function of the vascular wall. Alteration in the expression of these proteins is associated with endothelial dysfunction and has been implicated in the development and progression of atherosclerosis. The ECM composition of atherosclerotic plaques varies depending on plaque phenotype and vulnerability, with distinct differences observed between ruptured and erodes plaques. Moreover, the thrombi on the exposed ECM are diverse in structure and composition, suggesting that the best antithrombotic approach may differ depending on plaque phenotype. This review provides a comprehensive overview of the role of proteoglycans in atherogenesis and thrombosis. It discusses the differential expression of the proteoglycans in different plaque phenotypes and the potential impact on platelet function and thrombosis. Finally, the review highlights the importance of this concept in developing a targeted approach to antithrombotic treatments to improve clinical outcomes in cardiovascular disease.

Heat transfer mechanism in idealized healthy and diseased aortas using fluid-structure interaction method.

The heat transfer mechanism inside the human aorta may be related to the physiological function and lesion formation of the aortic wall. The objective of this study was to acquire the temperature distribution in the three-dimensional idealized aorta. An idealized healthy aortic geometry and three representative diseased aortas: aortic aneurysm, coarctation of the aorta, and aortic dissection were constructed. Advanced fluid-structure interaction (FSI) computational framework was applied to predict the aortic temperature distribution. The movement of the aortic root due to the heartbeat was also considered. The displacement distribution of the aortic vessel wall was consistent with clinical observation. The lesser curvature of the aortic arch, aneurysm body, coarctation region, and false lumen were all exposed to relatively high temperatures (over 310.006K). We found that the rigid wall assumption slightly underestimated the magnitude of the whole aortic wall-averaged temperature while the changing trend and local temperature were like the results of the FSI method. Besides, the wall-averaged temperature would increase and the temperature inflection point would advance when the aortic vessel wall was loaded with a high heat flux. This pilot study revealed the aortic heat transfer mechanism and temperature distribution, and the findings may help to understand the physiological characteristics of the aortic vessel wall.

Somatic mutations in vascular wall function and age-associated disease.

Somatic mutations in vascular wall function and age-associated disease.

Morphological changes in the anterior vaginal wall caused by aging: a scanning electron microscopy study.

Collagen is a protein that confers robustness and resilience to several tissues. In the female reproductive system, collagen plays a critical role in maintaining the health and function of the vaginal walls. Aging leads to collagen reduction, which may cause vaginal dryness, irritation, and prolapse. We aim to analyze the structure and profile of collagen in the anterior vaginal wall of healthy pre-menopausal (pre-M) and post-menopausal (post-M) women under a scanning electron microscope (SEM). Fragments of the anterior vaginal wall were collected and processed for light and scanning electron microscopy. Histological preparations were performed at first with Weigert's resorcin-fuchsin stain. Decellularized preparations were conducted, and the specimens were placed under an SEM to allow observation of the 3D organization of collagen. Decellularized preparations of the pre-M specimens showed a vaginal wall with an irregular subepithelial layer, organized with ECM projections. The subepithelium evidenced the network of collagen fibrils, which seemed to support the epithelium as a basal layer. In specimens of post-M, a fusion of a network of fibrils from different direction axes was evidenced, with plate formation observed in the subepithelial plane, disfiguring the structural organization of fibrils. Older specimens showed a remodeling of collagen organization in comparison with younger samples of the anterior vaginal wall.

Reconstruction of Nusselt number in RANS computations with wall function approach

Two novel methods for reconstruction of Nusselt number (Nu) are proposed when the wall function approach is used in the RANS framework for defining wall boundary conditions for high Reynolds number flows. The work is motivated by the observation that the velocity and temperature fields are often well predicted when the wall function formulations are used, while at the same time Nu is not. The reason for discrepancy in predictions of flow fields and temperature, and prediction of Nu, is because Nu estimation is solely dependent on the wall function, while the variables obtained from the transport equations are determined also by the convection and pressure force in the momentum transport. The method based on the correction factor Ψ∗ originates from the simplified analytical wall function approach of Popovac and Hanjalić (2007) and modifies the formulation of so-called wall viscosity. The method based on a wall shape function of exponential type approximates temperature variation in the near-wall region. Once the shape function’s coefficients are calculated using values of temperature in three near-wall consecutive cells, the wall values of temperature or temperature gradient, needed for calculation of Nu, can be determined. The methods are tested for four standard benchmark cases, backward-facing step, impinging jet, differentially heated square cavity, and Rayleigh-Bénard convection. The method based on the correction factor significantly improved Nu predictions for the cases where the velocity field is strongly impacted by pressure force. The method based on the wall shape function improves predictions of Nu in all tested cases, with somewhat less accurate predictions of the maximum value of Nu compared to the correction factor method.

Right ventricular global longitudinal strain and short-term prognosis in patients with first acute coronary syndrome

Abstract Funding Acknowledgements Type of funding sources: None. Background Right ventricular (RV) dysfunction is recognized as an adverse prognostic feature in patients with Acute Coronary Syndromes (ACS). However, conventional echocardiographic indices for the evaluation of RV function have considerable limitations. Right Ventricular Global Longitudinal Strain (RV GLS) is a novel speckle-tracking echocardiographic index that assesses the overall intramyocardial function of the RV free wall and interventricular septum. Purpose The present study aimed to investigate the short-term prognostic value of RV GLS in patients with first ACS. Methods A total of 300 consecutive patients with first ACS (mean age 61.2±11.8 years, 74% males) were prospectively studied. A comprehensive transthoracic echocardiographic assessment was undertaken within 24 hours after revascularization and in-hospital mortality was assessed. Multiple multivariable Cox Regression analysis models were constructed to compare the predictive value of RV function indices for in-hospital mortality. Only significant variables (P<0.05) in the univariate analysis were included in the models. Due to the limited number of events, all multivariable models were constructed including a maximum of 3 variables. To further assess the prognostic value of RV GLS over a baseline model the change in χ2 was assessed using the likelihood ratio test. The absolute value of strain parameters was used for all analysis. Results Patients with anterior-STEMI had significantly more impaired RV GLS (anterior-STEMI 14.52±5.23 vs. inferior-STEMI 17.41±5.06 vs. lateral-STEMI 19.50±4.17 vs. Non-STEMI 20.61±3.69%, P<0.001). A total of 23 (7.7%) patients died in-hospital after revascularization. In univariate analysis RV GLS was significantly associated with in-hospital mortality (HR=0.717, 95% CI=0.642–0.801, P<0.001). After adjustment for Global Registry of Acute Coronary Event (GRACE) risk score and Left Ventricular Ejection Fraction (LVEF), RV function indices that retained independent association with in-hospital mortality were RV GLS, Fractional Area Change, and Tricuspid Annular Plane Systolic Excursion (Table). The model that included RV GLS demonstrated the highest overall χ2 value (Table). To prove the incremental value of RV GLS on in-hospital mortality prognosis, a baseline model including the GRACE risk score was created, and then LVEF was added. The further addition of RV GLS significantly increased the prognostic value the model (Figure). Conclusions RV GLS measured by transthoracic echocardiography within 24 hours after revascularization in patients with first ACS showed the strongest association with in-hospital mortality outperforming other RV function indices. RV GLS provides additine prognostic information over GRACE risk score and LVEF to predict in-hospital mortality.

Another Tool in the Quest for the Perfect Living Liver Donor Operation.

Living donor surgeons must balance donor safety with regard to bleeding, vascular injury, and biliary complications while minimizing short-term pain and long-term abdominal wall function. At the same time, living donor patients are usually deeply concerned about the recipient’s outcomes. Reduced donor morbidity at the cost of increased recipient complications is not acceptable. In this issue, Park et al report their experience with 448 consecutive donors who underwent living donor right hepatectomy by a single surgeon over the course of 5 y.1 One hundred eighty-seven of these donors underwent a mini-incision compared with the conventional J-shaped incision. The team functions within a center that performed more than 1600 donor right hepatectomies over the 5-y period. Right hepatectomy is a physiologically significant operation with risks related to loss of hepatic parenchyma. Many donor surgeons have argued that due to the risks of the surgery including hepatic failure, vascular injury, and biliary complications, the open approach should remain the primary approach.2 However, minimally invasive approaches have been introduced starting with Cherqui et al in 20023 and for right hepatectomies in 2013.4 Although a few centers have embraced the full laparoscopic approach for near donors, adoption broadly in the community of donor surgeons has been slow. Ten years after the initial right hepatectomy reports, fully laparoscopic donor hepatectomy surgery remains isolated to a few centers.5,6 As the authors mention, mini-incision, laparoscopy-assisted and hand-assisted approaches, have been introduced to minimize abdominal wall injury while reducing the learning curve associated with fully laparoscopic approach. Park et al show that excellent outcomes can be achieved for the donors and the recipients using an 8.5- to 13-cm right subcostal incision. They demonstrated low rates of biliary and vascular complications for both donors and recipients. Authors note that when they started mini-incision living donor right hepatectomy, they avoided larger liver and higher body mass index patients or patients with large inferior right hepatic veins. Later in their experience, they develop increased comfort with higher body mass index patients. Interestingly, at the authors’ institution, only 5% of the right hepatectomies are performed laparoscopically, and 3 of the 5 performing donor hepatectomies only perform mini-incision on selected patients. This rigorous selection of patients highlights challenges for broader application of smaller incisions even at the most experienced centers in the world. Making a minimally invasive donor operation safer, more easily reproducible, and with a shortened learning curve is the ideal all donor surgeons should be striving toward. Park et al have shown that mini-incision right donor hepatectomy can be part of that toolbox but likely the perfect operation is still out there waiting to be developed.

CFD investigation of flow and heat transfer of supercritical CO2 in wire wrapped rod bundle

Computational fluid dynamics is increasingly applied to reactor safety analysis, and the applicability evaluation of turbulence model can effectively improve the calculation accuracy. In this paper, the applicability of six turbulence models and two near wall models is compared for simulation of flow and heat transfer of supercritical carbon dioxide in wire wrapped rod bundle. According to experimental data under various conditions, the applicability of turbulence models and near wall models is respectively evaluated from wall temperature and surface heat transfer coefficient. The results show that SST k–ω model combined with low-Re model can simulate the change of wall temperature and surface heat transfer coefficient in critical state best, and the average relative error (Tw and h) is 6.88% and 13.17%. When CO2 is heated into supercritical state in the latter 900 mm of wire wrapped rod bundle, the relative error (Tw and h) calculated by RNG k–ω model is 5.94% and 18.02%. The grids number of low Re method is nearly double of the grids number of wall function method. Therefore, the simulation results computed by wall function method at supercritical region are also acceptable due to the low computational consumption. This paper researches the applicability of turbulence model and near wall model to enhance the accuracy of simulation of flow and heat transfer in supercritical CO2 reactor rod bundle.

Correlation between hydraulic loss and characteristic vorticities in a mechanical pump

The correlative mechanism between the flow loss and vortex evolution involves the efficiency and stability of space operations during fuel transportation in the on-orbit refueling and circulation systems. This study described detailed hydraulic loss and characteristic vorticity by adopting the entropy wall function and local hydraulic loss rate method that included dissipation and transportation effects. Combined with the correlation analysis, characterized vortex parameters and the distributions of dissipated and transported loss were compared based on the enstrophy method and rigid vorticity transport equation. The results exhibit that although dissipated hydraulic loss occupied a main proportion of the total loss, the transported loss cannot be ignored. The enstrophy for shear vorticity and vorticity transport strength of rigid vorticity are the dominant factors affecting the dissipation and transportation effects and hydraulic loss, respectively. Both dissipation and transportation effects of hydraulic loss are strongly related to shear enstrophy and weakly related to enstrophy for rigid vorticity. However, the correlation between the transport strength of rigid vorticity and the two effects of hydraulic loss was significantly enhanced. Based on this, four sub-items of rigid vorticity transport strength, including rigid vorticity stretching, vorticity dilatation, pseudo-Lamb vector, and viscous terms, were further investigated to elaborate the source of hydraulic loss. The correlations between the pseudo-Lamb vector with transported hydraulic loss were almost identical to that of rigid vorticity transport strength, indicating that the transported hydraulic loss is mainly derived from the shearing motion and local acceleration of vorticity.

Distribution Pattern and Influencing Factors for the Temperature Field of a Topographic Bias Tunnel in Seasonally Frozen Regions

In seasonally frozen regions, highway tunnels are prone to shallow buried bias pressures near the inlet/outlet, which leads to highway tunnels not only bearing asymmetric loads, but also facing the threat of extreme weather. However, there is still no clear understanding of the temperature field for topographically biased tunnel in seasonally frozen regions at present. Taking the Huitougou tunnel of Hegang-Dalian expressway as the object, this paper uses on-site monitoring, theoretical analysis, and numerical simulation to study the distribution law and influence factors of temperature field for topographically biased tunnel in seasonally frozen regions. The numerical results of the temperature field are in good agreement with the on-site monitoring data, which verified the accuracy of this numerical model based on the aerodynamic principle, turbulence model, and wall function method. Meanwhile, the effect of different slope angle and overburden thickness on the temperature field of the tunnel is further analyzed. It is found that when the slope angle increases, the temperature field in the tunnel surrounding rock changes accordingly. The connecting area between the surface and the tunnel temperature field is deflected from arch crown to the arch shoulder of the tunnel, resulting in a large change in the temperature of the shallow buried side, while minor change in the temperature of the deep buried side. The freezing depth of surrounding rock decreases with the rising slope angle. As the overburden thickness gradually increases, the temperature field of the surface surrounding rock and the tunnel surrounding rock gradually change from mutual influence to non-influence. When the overburden thickness exceeds 15 m, a “isolated temperature zone” appears in the middle with a temperature of 6~7 °C, the temperature field of the tunnel surrounding rock is basically not affected by the surface air temperature. These results can provide important theoretical and engineering guidance for the evaluation, construction, and maintenance of tunnel engineering in seasonally frozen regions.

ПРОМИСЛОВИЙ ЦИКЛОННО-РОТАЦІЙНИЙ ПИЛОВЛОВЛЮВАЧ

Cyclone equipment is easy to manufacture and operate, versatile and economical, but its main drawback is the inability to capture finely dispersed dust. The article discusses the most important characteristics of the highly efficient industrial cyclonic rotary dust collector developed by us. The apparatus implements the principle of two-stage separation of heterogeneous dust-gas systems in a centrifugal field. In the first stage, working on the principle of a cyclone, and in the second - working on the principle of a rotary dust collector. During operation of the apparatus, a higher pressure on the periphery of the rotating part returns a concentrated dusty flow with a low gas flow to the cyclone part. Formed by a gap, between the cyclone body and the dividing cone, a closed circuit connects the output and input of the cyclone-rotational dust collector to each other. There is a negative feedback - an effective control mechanism for such complex probabilistic systems as gas heterogeneous curvilinear flows. Negative feedback stabilizes the processes occurring in such flows. The energy of the electric motor is used in the cyclone-rotational dust collector for the movement of dusty gas, concentration, coagulation of fine dust, its return from the rotary to the cyclone zone, dispersion and capture, with the aim of saving energy and material resources. The main task of the theory of centrifugal separation of dusty flows is to find the minimum diameter of a particle that has a practically perceptible relative radial velocity. Known deterministic models of centrifugal separation are either too simple and ignore many factors that determine the process, or in attempts to account for them are too cumbersome and difficult to solve, although they are also not free from various assumptions and limitations. The stochastic model takes into account the integral set of various influences on the radial drift of the Stokes particle from the center to the periphery of the swirling flow. The paper presents the results of the study of the structure of the three-dimensional two-phase gas flow with highly dispersed inclusions in cyclonic-rotary dust collectors using 3D geometric models with the aim of visualizing these flows using computer graphics methods. Numerical studies were carried out using the k-e model of turbulence with scaled wall functions.

P137 STEMI IN YOUNG MAN: A "CHALLENGE" CASE OF SPONTANEOUS CORONARY DISSECTION

Abstract A 21–years old male patient presented to the emergency department complaining chest pain in the night. There was no family history of cardiovascular events; he did not have any known risk factors and denied drug abuse. Pathological history was positive for allergic asthma. On admission, he was paucisyntomatic. The physical examination was normal. Blood pressure was slightly elevated. The EKG showed sinus rhythm, ST segment elevation in high lateral leads and reciprocal ST depression in inferior leads. The echocardiogram showed anterolateral and mid–apical septal akinesia of the left ventricle with ejection fraction of 45%. The urgent coronary angiography showed suspected coronary artery dissection of the first diagonal branch with TIMI flow grade 2 and myocardial brigde of the middle segment of the left anterior descending artery (fig.1). An initial conservative management with beta–blockers, dual antiplatelet therapy, statin and ACE–inhibitors was adopted: the patient was asymptomatic and the EKG became normal during the coronary angiography. In addition the young age, the suspicion of Spontaneous Coronary Artery Dissection (SCAD) and TIMI flow grade 2 in the culpit vessel provided support of conservative treatment. The hospital stay was unremarkable. Troponin T peak value was 1542 pg/ml (n.v. < 13 pg/ml). Thrombophilia screening showed mild hyperhomocysteinemia and homozygous MTHFR mutation. Autoimmunity screening was negative. The subsequent echocardiogram showed mid–distal hypokinesia of the anterolateral, inferolateral and anterior wall of the left ventricle with normal ejection fraction. The CT angiography of the cerebral and abdominal vessels was normal. The cardiac magnetic resonance imaging (MRI) confirmed a recent acute myocardial infarction of the mid–apical portions of the anterior and anterolateral wall and normal global contractile function of the left ventricle (fig. 2, 3). At 30 days follow up, the echocardiogram remained unchanged; the coronary AngioCT scan confirmed the dissection of the ostium and proximal section of the first diagonal branch; the cardiac MRI showed transmural fibrosis of the anterolateral wall with normal left ventricular ejection fraction. SCAD is an under–reported pathology. It can lead to acute coronary syndromes and life–threatening consequences. Diagnosis and treatment are still under debate. The presented clinical case, effectively treated with conservative therapy, represented a "challenge" in the acute phase.

Study on dynamical characteristics of cooling fluid in engine piston

The cooling of engine piston is very important, and the fluid vibration characteristics of its internal cooling oil is the key to affect the heat transfer efficiency. In order to effectively ensure that the piston temperature will not be overloaded and avoid the reduction of sealing performance, a two-phase flow model in the piston cooling chamber is established in the paper. The flow field and heat transfer characteristics of the cooling oil are simulated by finite element method using FLUENT. In terms of model selection, VOF multiphase flow calculation and SST k-ω model are selected as turbulence model. The setting of boundary conditions combines the piston stroke characteristics of the hydraulic cylinder, so as to obtain accurate inlet parameters, and obtain the oil liquid phase proportion distribution, oil velocity field and the change law of convective heat transfer coefficient under different piston positions. The results show that the instantaneous ratio of cooling oil is closely related to the speed, and increasing the oil speed is an important means to improve the heat transfer performance. The multiphase flow model has high reliability, and there is no obvious difference between the average convective heat transfer coefficient obtained by the near-wall model method and the wall function method.

Forced convective heat transfer and fluid flow past a rotating hand-shaped former for improving rubber glove curing

In the present pandemic, rubber gloves have been extensively used in the medical and healthcare fields. However, the increase in production capability to meet the accelerating demand deteriorated the curing process of the rubber gloves, which led to poor quality gloves. In this study, forced convective heat transfer around a rotating hand-shaped former was analyzed using computational fluid dynamics (CFD) to improve the rubber glove curing process. To this end, a 3-D scanner modeled a typical hand-shaped former for the moving reference frame in the CFD model. Further, an SST k-ω turbulence model and its wall functions were applied with OpenFOAM software. The constant dimensionless rotation rate (α) was varied from 0 to 5 in the Re∞ range 1583–15,837, which is same as that in manufacturing process. The simulation results agreed well with the experimental data. The results confirmed that the convective heat transfer of the individual section and entire body varied according to variables Re∞ and α. The rotation rate affected the heat transfer in the finger gaps. This former segment was affected by forced convective heat transfer, as justified by the analysis of variance. Therefore, a novel average Nusselt number governing the heat transfer around the middle finger was proposed. This equation depends on the former geometry, rotation rate, and airflow velocity, which are significant for setting up the curing process and rapidly improving rubber gloves.

Impact of high-fat diet on mitochondrial dynamics in Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is an asymptomatic pathology, representing more than 75% of aortic aneurysms. It is characterized by a significant dilation of the aortic wall, which usually lead to severe complications as aneurysm rupture. Surgical repair (open or endovascular) is currently the only treatment available for AAA. As obesity is an established as a risk factor for cardiovascular disease, lipid metabolism involvement in AAA is not clearly understood. It would therefore be interesting to study its impact on mitochondrial dynamics, whose bioenergetic functions are necessary to maintain the function and integrity of the aortic wall. Our aim is to study the impact of lipid metabolism on mitochondrial dynamics in abdominal aortic aneurysm. We used a murine model of 6 months old of hypertensive Ldlr-/- male mice (angiotensin II, 1 mg/kg/day) fed with a standard diet (ND) or high-fat diet (HFD) for 28 days. Supra-renal abdominal aorta segment was removed to perform transcriptional and protein analysis (RT-qPCR and Western blot respectively) of the mitochondrial homeostasis actors. For HFD fed mice, we found an obvious obesity of Ldlr-/- hypertensive mice. Our results revealed a similar incidence of abdominal aortic aneurysm and mortality rate, between ND and HFD hypertensive Ldlr-/- mice. In these two groups, mice suffering from an abdominal aortic aneurysm showed a significant decrease, in mitochondrial fusion (Mfn1/2) and fission (Dnml1) transcript expression. Moreover, DRP1 protein expression and the mitophagy protein, PARKIN, are increased only in Ldlr-/- hypertensive ND mice. However, no significant difference was found with Ldlr-/- hypertensive HFD mice. These preliminary data suggest that the obesity observed in Ldlr-/- hypertensive mice by the HFD, has no impact on the development of the aortic aneurysm, as well as on mitochondrial homeostasis.