Use Of Computational Fluid Dynamics Simulations Research Articles

Application of Computational Fluid Dynamic Simulation of Parent Blood Flow in the Embolization of Unruptured A1 Aneurysms

To investigate the effect of microcatheter shaping based on the parent artery mainstream line of blood flow simulated using the computational fluid dynamics (CFD) technique on embolization of unruptured aneurysms on the posterior wall of the anterior cerebral artery (ACA) A1 segment. Patients with unruptured cerebral aneurysms on the posterior wall of the ACA A1 segment were retrospectively enrolled and treated with endovascular embolization after microcatheter shaping. The clinical, embolization, and follow-up data were analyzed. Eight patients were enrolled and treated with endovascular embolization. 8 microcatheters were steam-shaped invitro and were all successfully navigated to the right location in the invitro experiment. During the embolization procedure, 7 microcatheters were successfully navigated to the right location for embolization. In the remaining 1 patient who had tortuous cerebral arteries, reshaping of the microcatheter based on the parent artery mainstream of blood flow made successful navigation of the microcatheter to the right place. Complete occlusion was obtained in 7 (87.5%) aneurysms and residual aneurysm neck in the remaining 1 (12.5%). At angiographic follow-up in 6 (75%) patients, the Raymond grade was I in 5 (83.3%) and II in the rest 1 (16.7%). Use of computational fluid dynamics simulation of parent artery blood flow for microcatheter shaping in the embolization of unruptured aneurysms on the posterior wall of the ACA A1 segment is safe and effective in navigating the microcatheter to the right location for embolization, resulting in good stability and support for the embolization.

Application of computational fluid dynamics simulation in predicting food protein denaturation: numerical studies on selected food products - a review*

Abstract Protein denaturation is a common process in the food industry, which can impact food quality and safety. Computational Fluid Dynamics (CFD) is a powerful tool that can be used to predict protein denaturation in food products. In this review article, we present an overview of the application of CFD simulation in predicting protein denaturation in food products. We discuss the factors that influence protein denaturation, the importance of predicting protein denaturation, and the various numerical methods used in protein denaturation studies. The main focus of the article is the use of CFD simulation in predicting protein denaturation in selected food products, such as milk, meat, and eggs. We provide examples of numerical studies that have been conducted on these products, and we discuss the results and implications of these studies. The use of CFD simulation can help to optimize food processing conditions, improve food quality and safety, and reduce waste and costs in the food industry. Overall, this review article highlights the importance of using advanced computational tools such as CFD simulation in food science, research and development. Highlights The use of CFD simulation can predict protein denaturation in food products. Numerical studies were conducted on selected food products to analyze protein denaturation. CFD simulation provides a powerful tool for optimizing food processing technologies. The results from the numerical studies can be used to improve the quality and safety of food products. The application of CFD simulation can lead to more efficient and sustainable food production practices.

OF2: coupling OpenFAST and OpenFOAM for high-fidelity aero-hydro-servo-elastic FOWT simulations

Abstract. The numerical study of floating offshore wind turbines (FOWTs) requires accurate integrated simulations which consider the aerodynamic, hydrodynamic, servo and elastic responses of these systems. In addition, the floating system dynamics couplings need to be included to calculate the excitation over the ensemble accurately. In this paper, a new tool has been developed for coupling NREL's aero-servo-elastic tool OpenFAST with the computational fluid dynamics (CFD) toolbox OpenFOAM. OpenFAST is used to model the rotor aerodynamics along with the flexible response of the different components of the wind turbine and the controller at each time step considering the dynamic response of the platform. OpenFOAM is used to simulate the hydrodynamics and the platform's response considering the loads from the wind turbine. The whole simulation environment is called OF2 (OpenFAST and OpenFOAM). The OC4 DeepCWind semi-submersible FOWT together with NREL's 5 MW wind turbine has been simulated using OF2 under two load cases. The purpose of coupling these tools to simulate FOWT is to obtain high-fidelity results for design purposes, thereby reducing the computational time compared with the use of CFD simulations both for the rotor aerodynamics, which usually consider rigid blades, and for the platform's hydrodynamics. The OF2 approach also allows us to include the aero-servo-elastic couplings that exist on the wind turbine along with the hydrodynamic system resolved by CFD. High-complexity situations of floating offshore wind turbines, like storms, yaw drifts, weather vanes or mooring line breaks, which imply high displacements and rotations of the floating platform or relevant non-linear effects, can be resolved using OF2, overcoming the limitation of many state-of-the-art potential hydrodynamic codes that assume small displacements of the platform. In addition, all the necessary information for the FOWT calculation and design processes can be obtained simultaneously, such as the pressure distribution at the platform components and the loads at the tower base, fairleads tension, etc. Moreover, the effect of turbulent winds and/or elastic blades could be taken into account to resolve load cases from the design and certification standards.

CARD20: Investigating the Impact of Ventriculoatrial Shunts on Venous Hydrodynamics: A Computational Fluid Dynamics Analysis

Ventriculoatrial (VA) shunts are a common treatment option for patients suffering from hydrocephalus and requiring cerebrospinal fluid (CSF) drainage. However, the impact of this treatment on cardiac hydrodynamics has yet to be fully understood. To shed light on this issue, the present study employs computational fluid dynamics (CFD) simulations to evaluate the effects of VA catheters on venous hydrodynamics in hydrocephalus patients. The study focuses on five models of different sections of veins, including the Internal Jugular Vein (IJV), Right and Left Brachiocephalic Veins (RBV-LBV), and the Superior Vena Cava (SVC). The vein geometry was reconstructed from neck CT scans of a patient with mild hydrocephaly without a catheter. Blood flow simulations were performed using pressure-based transient laminar models solved with the Ansys Fluent Navier-Stokes solver. The analysis was conducted on two healthy cases with and without catheters, and three hydrocephalus cases with catheters, considering mild, moderate, and severe hypertension. The results show that pressure accumulation near the IJV bulb was observed in all cases, with maximum pressure in the severe hypertension case. A pressure of 3,050 Pa was reached over the catheter insertion site. The healthy case without the shunt showed velocities of up to 0.8 m/s, while in the severe hypertension case, velocities were less than 0.2 m/s in similar regions for the IJV, RBV, and LBV. Healthy streamlines showed some vortices throughout the IJV, which seemed to be minimized by the presence of the catheter in the other models. In conclusion, this study provides valuable information regarding the hydrodynamic alterations seen in patients with VA shunts. The observed pressure accumulation and decreased velocity can be associated with potential adverse effects such as thrombotic formation. These findings can be used to guide future treatment options and warrant further long-term study. The use of CFD simulations offers a non-invasive and efficient method to study the effects of VA shunts on cardiac hydrodynamics and can provide a deeper understanding of the complex interplay between cerebrospinal fluid drainage and venous hydrodynamics.

Influence of Tubercle Modifications on the Performance of Marine Vertical Axis Propellers

Even though past efforts in computational fluid dynamics (CFD) simulations have shown great progress in the implementation of tubercles into aero-foils and turbines blades, incorporating these tubercles into marine vertical axis propellers is still comparatively less well understood. In general, the performance of marine propellers is highly related to the pressure and velocity distributions over the propeller blades. Since the presence of tubercles’ serrations in the blade leading edge can vary these distributions over the blade, the performance of the propellers can be enhanced. In this article, tubercle modifications are investigated in marine vertical axis propellers through the use of CFD simulation. To achieve this purpose, a complete procedure of CFD simulation using ANSYS FLUENT 16 is proposed. Obtained CFD results are validated using direct comparison with the previous analytical studies. Obtained performance characteristics of the modified vertical axis propeller are assessed against the available characteristics of the baseline one. The CFD results are found in a good agreement with the analytical ones. Moreover, the results demonstrate the improvement of the obtained performance of the modified vertical axis propeller compared to the baseline one in terms of increased thrust coefficient and higher efficiency over the considered range of advance ratio.

Recent Progresses in Verification, Validation and Uncertainly Analysis in Computational Fluid Dynamic

Verification and validation (V&V) are indispensable tools to evaluate the accuracy and reliability in computational simulations. This paper highlights guidelines, related works, as well as recent progresses for evaluating the credibility of model and simulation in computational fluid dynamics (CFD). Herein, detailed definitions of V&V that aims to help researchers to distinguish between the term verification and the term validation, define the conceptual sources of error and uncertainty as well as understanding the difference between them. Then, we discuss related works to V&V for CFD simulations, the most useful methodologies and algorithms have been introduced, problems have been faced as well as solutions has been proposed. Finally, an outlook and perspectives for future challenges in V&V for CFD Simulation have been proposed. For verification assessment, in order to assure the accuracy, the computational solution is compared with an analytical solution or a highly accurate solution. The main strategy of validation is to reflect the accuracy between the computational results and the experimental data, as well as the quantification and estimation of both error and uncertainty. It is hoped from this review to help in research, development as well as the use of CFD simulations by establishing robust methodologies and terminologies for V&V.

Automatic triangulated mesh generation of pulmonary airways from segmented lung 3DCTs for computational fluid dynamics.

Computational fluid dynamics (CFD) of lung airflow during normal and pathophysiological breathing provides insight into regional pulmonary ventilation. By integrating CFD methods with 4D lung imaging workflows, regions of normal pulmonary function can be spared during treatment planning. To facilitate the use of CFD simulations in a clinical setup, a robust, automated, and CFD-compliant airway mesh generation technique is necessary. We define a CFD-compliant airway mesh to be devoid of blockages of airflow and leaks in the airway path, both of which are caused by airway meshing errors that occur when using conventional meshing techniques. We present an algorithm to create a CFD-compliant airway mesh in an automated manner. Beginning with a medial skeleton of the airway segmentation, the branches were tracked, and 3D points at which bifurcations occur were identified. Airway branches and bifurcation features were isolated to allow for automated and careful meshing that considered their anatomical nature. We present the meshing results from three state-of-the-art tools and compare them with the meshes generated by our algorithm. The results show that fully CFD-compliant meshes were automatically generated for an ideal geometry and patient-specific CT scans. Using an open-source smoothed-particle hydrodynamics CFD implementation, we compared the airflow using our approach and conventionally generated airway meshes. Our meshing algorithm was able to successfully generate a CFD-compliant mesh from pre-segmented lung CT scans, providing an automatic meshing approach that enables interventional CFD simulations to guide lung procedures such as radiotherapy or lung volume reduction surgery.

Kajian Parametrik Analisis Terma Bumbung Menggunakan Teknik Berangka

The ever-increasing temperature of current climate has brought the attention on reducing the incoming solar heat energy into buildings. The efforts on reducing the dependency on air-conditioning for indoor cooling has led to the implementation of passive cooling strategies in buildings. This paper investigates the implementation of reflective technologies in the form of reflective insulation and radiant barrier systems in a gable roof assembly. The thermal performance of reflective insulation and radiant barrier systems was investigated by using Computational Fluid Dynamics (CFD) simulation. The thermal performance of the reflective technologies was presented in terms of thermal resistivity, RSI value. The study was conducted for several roof configurations where the thickness of reflective air space, roof pitch and the roof material were varied. The results obtained from the CFD simulation was validated against empirical measurements to ensure the simulation gives high accuracy prediction. From the parametric analysis, it was found that thicker reflective air space would provide better air ventilation in the air space area which led to higher thermal resistivity. Besides that, steeper roof pitch would enhance the buoyancy effect and increases the heat exhaustion through the ridge which also results in higher thermal resistivity. In terms of roof tiles material, only small difference was observed in terms of thermal resistivity when switching the roof tiles material between clay tiles and concrete tiles. This research was able to demonstrate the use of CFD simulation in investigating thermal insulation technologies in buildings and this method should be explored further in the future.

Recent progress in multiphase flow simulation through multiphase pumps

AbstractThe multiphase flow pumps cover a wide range of industrial sectors extending across petrochemical, metallurgy, and dredging, chemical industry, paint, and construction. The major application is the handling of wet gas and vapor that will condense partially during the compression stage. The main progress in the area of multiphase pumps has been the innovation of a computational fluid dynamics (CFD) numerical approach to simulate three‐dimensional flows inside the pump and to predict pump performance. CFD undoubtedly constitutes one of the most promising approaches for the design, analysis, and performance assessment of complex machines. However, practical application of the CFD tool to determine the internal flow field in multiphase pumps is still far from reality owing to the limitations of a detailed three‐dimensional model of the pump and accuracy of multiphase flow simulation. This review accentuates the influence of different geometrical and dynamical parameters on the performance of the pump and the use of CFD simulation to predict the detailed flow patterns of fluid mixtures. CFD analysis has unearthed the fact that the pattern of inner flow varies with the flow rate and concentration of each phase and the rotation speed of the impeller and number of blades were also found to considerably impact pump performance.

Kajian Parametrik Analisis Terma Bumbung Menggunakan Teknik Berangka

The ever-increasing temperature of current climate has brought the attention on reducing the incoming solar heat energy into buildings. The efforts on reducing the dependency on air-conditioning for indoor cooling has led to the implementation of passive cooling strategies in buildings. This paper investigates the implementation of reflective technologies in the form of reflective insulation and radiant barrier systems in a gable roof assembly. The thermal performance of reflective insulation and radiant barrier systems was investigated by using Computational Fluid Dynamics (CFD) simulation. The thermal performance of the reflective technologies was presented in terms of thermal resistivity, RSI value. The study was conducted for several roof configurations where the thickness of reflective air space, roof pitch and the roof material were varied. The results obtained from the CFD simulation was validated against empirical measurements to ensure the simulation gives high accuracy prediction. From the parametric analysis, it was found that thicker reflective air space would provide better air ventilation in the air space area which led to higher thermal resistivity. Besides that, steeper roof pitch would enhance the buoyancy effect and increases the heat exhaustion through the ridge which also results in higher thermal resistivity. In terms of roof tiles material, only small difference was observed in terms of thermal resistivity when switching the roof tiles material between clay tiles and concrete tiles. This research was able to demonstrate the use of CFD simulation in investigating thermal insulation technologies in buildings and this method should be explored further in the future.

Experiments and transient simulation on spring-loaded pressure relief valve under high temperature and high pressure steam conditions

Reliable performances of high temperature and high pressure operating steam pressure relief valves (HTHP PRVs) are extremely important for the safety of nuclear power plants. It is still a challenge to accurately describe the dynamic performance of HTHP PRVs. In this study, the accuracy of computational fluid dynamics (CFD) based modelling of the transient processes is examined. For one of the HTHP PRVs named DWPRV, the effects of different parameters on the dynamic performance were investigated by combining CFD simulation and experiments. In the simulation, the domain decomposition method (DDM) and the Grid Pre-deformation Method (GPM) were adopted to handle the moving disk geometry and the large mesh deformation. The effect of damping was also studied. It is confirmed that the use of CFD simulation can improve the design and settings of a HTHP PRV in a highly energetic service that is difficult to test due to safety reasons. For the DWPRV, it was found that the maximum flow rate occurs when the curtain area is 1.18 times the throat area. The degree of superheat ranging from 0 °C to 100 °C has a negligible effect on the performance of DWPRV regardless of the changes in the material mechanical properties with operating temperatures. The reseating pressure increases linearly with the rise in the distance between the upper adjusting ring and the sealing face. The lower adjusting ring exhibits a weak effect on the reseating pressure. For the ratios of rated lift to throat diameter equaling to 0.3 and 0.35, the DWPRV exhibits the higher blowdown for the ratio of 0.35.

Treatment strategy and follow-up evaluation for an unruptured anterior communicating artery aneurysm associated with pseudo-occlusion of the internal carotid artery using computational fluid dynamics simulations.

Basic research on cerebral aneurysms using computational fluid dynamics (CFD) simulations has recently progressed. We describe a clinical case with the use of CFD simulations. A 76-year-old woman had an unruptured anterior communicating artery aneurysm associated with pseudo-occlusion of the internal carotid artery (ICA). Pre-operative CFD simulations demonstrated that carotid artery stenting (CAS) would decrease hemodynamic stress on the aneurysm and might reduce the risk of aneurysm rupture. We performed CAS, and did not surgically treat the aneurysm because of her advanced age. A 7-month follow-up angiogram showed no change in the aneurysm size. We performed CFD simulations using the patient-specific flow waveforms at the bilateral ICAs before and 7 months after CAS. Maximum time-averaged wall shear stress of the aneurysm decreased from 8.3 Pa to 4.4 Pa. The pressure loss coefficient of the aneurysm, a proposed hemodynamic value for rupture risk, increased from 1.83 to 2.75. These findings indicated that CAS might reduce the rupture risk of the aneurysm according to previous reports on CFD studies. The aneurysm remains unruptured for 14 months from the CAS. This is the first report to attempt to reduce the rupture risk of an unruptured aneurysm with flow alteration based on CFD simulations.

Heavy Gas Dispersion Modelling Over a Topographically Complex Mesoscale: A CFD Based Approach

Potentially dangerous events involving heavy gas dispersion and their severe consequences have been largely publicized by the media. Simplified models have been widely applied to describe the effects of these accidents. However, most simplified models deal with flat terrain scenarios and are based on quite crude simplifications of the complex phenomenology involved. In this paper the possibility of simulating the dispersion of heavy gas clouds over a large topographically complex area (tens of km) by a general purpose computational fluid dynamics (CFD) code is investigated. The aim is that of setting up a tool able to produce a realistic description of such dispersion processes, whose results can be useful in considering the question of when and by how much one can be misled by a simplified model. The paper is divided in two parts: the first part describes the use of CFD simulations to generate the micrometeorological parameters which characterize the site before the release of the toxic material, while the second part deals with the dispersion process itself. The geographical region examined is the industrial site of Priolo-Gargallo/Augusta in the eastern part of Sicily, covering an extension of 30 × 30 km 2 .