Flow Velocity Patterns Research Articles

Velocity Distributions around Blocked Trash Racks

AbstractTransported debris in open channels can lead to accumulations and, therefore, cause blockages at trash racks. Velocity distributions and flow patterns change because of these blockages and ...

Dynamic behaviors of anisodiametric bubbles under effects of horizontal attraction and vertical wake

The present study aims to describe the interaction between rising bubbles of different sizes. Coaxial and triangle bubble configurations were investigated. Bubble sizes ranged from 4.0 mm to 10.0 mm. Three-dimensional unsteady numerical simulations were performed and the volume of fluid multiphase model was employed. The numerical scheme was validated through experimental results. Time-dependent bubble geometry, bubble velocity, and near-bubble flow patterns were obtained. The results show that the participation of lateral bubbles causes coalescence delay. The mergence of bubbles is followed by an immediate decrease in bubble velocity. Liquid flow structures tend to be combined accordingly as the bubbles coalesce. For the triangle configuration, the first coalescence of small bubbles takes place between the trailing bubbles. As bubble size increases, the first coalescence arises between the leading bubble and the left trailing bubble.

Preservation of left ventricle peak and mean pulse flow blood velocity despite progressive deterioration of cardiac function in a chronic heart failure murine model.

The goal of this study was to assess the alterations in left ventricle (LV) blood flow velocity patterns in relation to progressive impairment of cardiac function in the course of heart failure (HF) in a unique murine model of chronic HF in Tgαq*44 mice. Doppler- and MRI-based assessments of blood velocity and cardiac performance, respectively, were performed in Tgαq*44 mice at the age of 1, 2, 4, 6, 8 and 12 months as compared with age-matched FVB control mice. One-month-old Tgαq*44 mice displayed elongated early diastolic phase with fully preserved cardiac function that, however, progressively deteriorated in older Tgαq*44 mice. As early as in 2-month-old Tgαq*44 mice, the filling rate (FR), max. radial strain and end-systolic volume increased; in 4-month-old Tgαq*44 mice, the ejection fraction, max. circ. strain and ventriculo-arterial coupling decreased, and the ejection time was prolonged; in 6 - 8-month-old Tgαq*44 mice, the stroke volume, max. (both) strains decreased, end-systolic volume, FR and end-diastolic volume increased, and finally, in 12-month-old Tgαq*44 mice, the ejection fraction, cardiac output and stroke volume were all severely impaired. In the early phase of HF development, no differences were observed in Tgαq*44 mice versus FVB mice regarding systolic LV flow pattern, but indices of mitral diastolic flow were considerably increased in 1-month-old Tgαq*44 mice versus FVB mice. In the late phase of HF, despite progressive deterioration of cardiac function, LV pulse flow blood velocity was not altered in Tgαq*44 mice up to the age of 8 months. Systolic peak velocity and mean acceleration time deteriorated only in 12-month-old Tgαq*44 mice, with peak acceleration and mean velocity values still preserved. We demonstrated that the cardiac mitral diastolic flow pattern displayed adaptive changes in the very early phase of HF development in Tgαq*44 mice and that these changes preceded early alterations in LV haemodynamics. Then, despite the progressive deterioration of cardiac haemodynamics, peak and mean in- and out-flow velocities remained unchanged for a relatively long time and deteriorated only at the end-stage HF. Altogether, we revealed that in addition to cardiac performance, adaptive vascular performance represents an important factor determining LV mitral inflow and ejection flow phenotype during the progression of chronic HF in Tgαq*44 mice.

Surges of Harald Moltke Bræ, north-western Greenland: seasonal modulation and initiation at the terminus

Abstract. Harald Moltke Bræ, a marine-terminating glacier in north-western Greenland, shows episodic surges. A recent surge from 2013 to 2019 lasted significantly longer (6 years) than previously observed surges (2–4 years) and exhibits a pronounced seasonality with flow velocities varying by 1 order of magnitude (between about 0.5 and 10 m d−1) in the course of a year. During this 6-year period, the seasonal velocity always peaked in the early melt season and decreased abruptly when meltwater runoff was maximum. Our data suggest that the seasonality has been similar during previous surges. Furthermore, the analysis of satellite images and digital elevation models shows that the surge from 2013 to 2019 was preceded by a rapid frontal retreat and a pronounced thinning at the glacier front (30 m within 3 years). We discuss possible causal mechanisms of the seasonally modulated surge behaviour by examining various system-inherent factors (e.g. glacier geometry) and external factors (e.g. surface mass balance). The seasonality may be caused by a transition of an inefficient subglacial system to an efficient one, as known for many glaciers in Greenland. The patterns of flow velocity and ice thickness variations indicate that the surges are initiated at the terminus and develop through an up-glacier propagation of ice flow acceleration. Possibly, this is facilitated by a simultaneous up-glacier spreading of surface crevasses and weakening of subglacial till. Once a large part of the ablation zone has accelerated, conditions may favour substantial seasonal flow acceleration through seasonally changing meltwater availability. Thus, the seasonal amplitude remains high for 2 or more years until the fast ice flow has flattened the ice surface and the glacier stabilizes again.

Wall shear stress angle determines aortic growth in patients with bicuspid aortic valves

Abstract Funding Acknowledgements Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): The Dutch Heart Foundation Background Patients with bicuspid aortic valve (BAV) have altered flow velocity patterns with different wall shear stress (WSS) distributions in the ascending aorta compared to patients with tricuspid aortic valves. These WSS distributions are associated with aortic dilatation in cross sectional studies, however, longitudinal data demonstrating a potential causative role is missing. Purpose The aim of this study was to assess the differences in WSS distributions between BAV patients and healthy subjects and to determine the predictive value of WSS for aortic growth in patients with a BAV. Methods Forty patients with a BAV and 32 healthy matched subjects were prospectively studied by 4D-flow cardiovascular magnetic resonance (CMR). Peak velocity, pulse wave velocity, aortic distensibility, peak systolic WSS (magnitude), the different WSS components (axial and circumferential), and WSS angle were assessed in the proximal ascending aorta. WSS angle was defined as the angle between the WSSmagnitude and WSSaxial component. In the BAV patients, aortic volumetric growth over three years was determined in the proximal ascending aorta (first 5cm) based on CT angiography. Multivariate linear regression analysis was used to identify independent predictors of aortic volumetric growth. Results Of the BAV patients, 21 (53%) had a left-right fusion pattern and eight patients had Turner syndrome. WSSaxial was significantly lower in BAV patients compared to healthy subjects (p = 0.008) and WSScircumferential and WSS angle were significantly higher (both p < 0.001, see Figure). WSSmagnitude, pulse wave velocity, and aorta distensibility were not statistically significant different. WSSmagnitude (0.69 N/m² [0.51-0.81] vs 1.08 N/m² [0.89-1.24], p = 0.005), WSSaxial (0.50 N/m² [0.39-0.61] vs 0.72 N/m² [0.54-0.94], p = 0.015) and WSScircumferential (0.34 N/m² [0.32-0.46] vs 0.64 N/m² [0.47-0.81], p = 0.008) were significantly lower in BAV Turner patients compared to BAV non-Turner patients, while WSS angle (40° [34-41] vs 40° [32-48], p = 0.607) was not statistically significant different. During a follow-up of three years, there was a significant growth of the proximal ascending aorta in the BAV patients (1.2 cm3 [-0.2-2.5], p = 0.001). In multivariate analysis corrected for baseline aortic volume and diastolic blood pressure, WSS angle was the only independent predictor for proximal aortic volume growth (β=0.108, p = 0.030). Conclusions Increased WSScircumferential and especially WSS angle are present in patients with BAV. WSS angle was the only independent predictor of aortic growth. These findings highlight the potential role of WSS measurements in patients with BAV to stratify patients at risk for aortic dilation.

Numerical assessment of natural respiration and particles deposition in the computed tomography scan airway with a glomus tumour

The human respiratory tract has a complex airflow pattern. If any obstruction is present in the airways, it will change the airflow pattern and deposit particles inside the airways. This is the concern of breath quality (inspired air), and it is decreasing due to the unplanned production of material goods. This is a primary cause of respiratory illness (asthma, cancer, etc.). Therefore, it is important to identify the flow characteristics in the human airways and airways with a glomus tumour with particle deposition. A numerical diagnosis is presented with an asymmetric unsteady-state light breathing condition (10 l/min). An in vitro human respiratory tract model has been reconstructed using computed tomography scan techniques and an artificial glomus tumour developed 2 cm above a carina on the posterior wall of the trachea. The transient flow characteristics are numerically simulated with a realizable (low Reynolds number) k–ɛ turbulence model. The flow disturbance is captured around the tumour, which influenced the upstream and downstream of the flow. The flow velocity pattern, wall shear stress and probable area of inflammation (hotspot) due to suspended particle deposition are determined, which may assist doctors more effectively in aerosol therapy and prosthetics of human airways illness.

Cardiovascular fetal-to-neonatal transition: an in silico model.

Previous models describing the fetal-to-neonatal transition often lack oxygen saturation levels, homeostatic control mechanisms, phasic hemodynamic signals, or describe the heart with a time-varying elastance model. We incorporated these elements in the adapted CircAdapt model with the one-fiber model for myocardial contraction, to simulate the hemodynamics of the healthy term human fetal circulation and its transition during the first 24 h after birth. The fetal-to-neonatal model was controlled by a time- and event-based script of changes occurring at birth, such as lung aeration and umbilical cord clamping. Model parameters were based on and validated with human and animal data. The fetal circulation showed low pulmonary blood flow, right ventricular dominance, and inverted mitral and tricuspid flow velocity patterns, as well as high mean ductus venosus flow velocity. The neonatal circulation showed oxygen saturation levels to gradually increase to 98% in the first 15 min after birth as well as temporary left ventricular volume overload. Hemodynamics of the term fetus and 24-h-old neonate, as well as the events occurring directly after birth and the transition during the first 24 h after birth, were realistically represented, allowing the model to be used for educational purposes and future research. With the addition of oxygen saturation levels, homeostatic pressure-flow control mechanisms, and the one-fiber model for myocardial contraction, a new closed-loop cardiovascular model was constructed to give more insight into the healthy term human fetal circulation and its cardiovascular transition during the first 24 h after birth. Extensive validation confirmed that the hemodynamics of the term fetus and the fetal-to-neonatal transition were realistically represented with the model. This well-validated and versatile model can serve as an education as well as a research platform for in silico investigation of fetal-to-neonatal hemodynamic changes under a wide range of physiological and pathophysiological conditions.

Detachment of coal fines deposited in proppant packs induced by single-phase water flow: Theoretical and experimental analyses

Hydraulic fracturing is an effective approach to improve the productivity of coalbed methane (CBM) reservoirs. However, during hydraulic fracturing and CBM production, massive coal fines are deposited on the surface of proppants, leading to a sharp reduction in fracture conductivity. Herein, the detachment of deposited coal fines, caused by single-phase water flow in proppant packs, was investigated to elucidate the release mechanism of fines, which would be applied towards their effective removal in the field. First, coal fines detachment experiments, including permeability and effluent measurements, were conducted on proppant packs under saturated conditions. The experiments were performed with different sizes of coal fines and gradual/abrupt increases in flow velocity to study the effects of fines size and the variation pattern of flow velocity on the release of coal fines. The experimental results indicated that there existed a critical flow velocity (CFV) for the release of coal fines in proppant packs. The value of CFV decreased at first, and then increased with the increase in fines size. Additionally, both the amounts of fines produced and the increases in permeability were more pronounced under a gradual increase in flow velocity than those under an abrupt increase in flow velocity. Second, based on Happel's sphere-in-cell model, the forces/torques acting on the deposited coal fines were analyzed to illustrate the mechanisms underlying the release of fines in proppant packs. The theoretical results revealed that, with the increase in flow velocity, the release of fines began at the proppant midpoint and ended at the front and rear stagnation points. Theoretical CFV, corresponding to the detachment flow velocity of fines at the midpoint, first decreased with the increase in fines size and then increased. Theoretical CFVs were consistent with the experimental data, thus validating the proposed model. Finally, the implications of this research on the removal of coal fines in proppant packs were also discussed.

Hemodynamic conditions that favor bleb formation in cerebral aneurysms

BackgroundAlthough it is generally believed that blebs represent weaker spots in the walls of intracranial aneurysms (IAs), it is largely unknown which aneurysm characteristics favor their development.ObjectiveTo investigate possible associations...

A Convolution Method to Assess Subgrid‐Scale Interactions Between Flow and Patchy Vegetation in Biogeomorphic Models

AbstractInteractions between water flow and patchy vegetation are governing the functioning of many ecosystems. Yet, numerical models that simulate those interactions explicitly at the submeter patch scale to predict geomorphological and ecological consequences at the landscape scale (order of km2) are still very computationally demanding. Here, we present a novel and efficient convolution technique to incorporate biogeomorphic feedbacks in numerical models across multiple spatial scales (from less than 1 m2 to several km2). This new methodology allows for spatially refining coarse‐resolution hydrodynamic simulations of flow velocities (order of m) around fine‐resolution patchy vegetation patterns (order of 10 cm). Although flow perturbations around each vegetation grid cell are not simulated with the same level of accuracy as with more expensive finer‐resolution models, we show that our approach enables spatial refinement of coarse‐resolution hydrodynamic models by resolving efficiently subgrid‐scale flow velocity patterns within and around vegetation patches (mean error, spatial variability, and spatial correlation improved by, respectively, 13%, 66%, and 49% on average in our test cases). We also provide evidence that our approach can substantially improve the representation of important biogeomorphic processes, such as subgrid‐scale effects on net sedimentation rate and habitable surface area for vegetation (respectively 66% and 39% better on average). Finally, we estimate that replacing a fine‐resolution model by a coarser‐resolution model associated with the convolution method could reduce the computational time of real‐life fluctuating flow simulations by several orders of magnitude. This marks an important step forward toward more computationally efficient multiscale biogeomorphic modeling.

Pool‐Riffle Adjustment Due to Changes in Flow and Sediment Supply

AbstractHow do gravel bed pool‐riffle streams adjust to changing upstream water and bedload sediment supplies, and what analysis techniques can help to effectively identify how change occurs? Here, we use a mixture of field and experimental data to examine these problems and apply a suite of traditional and novel analysis approaches to highlight dynamics which might otherwise go undetected. Eleven years of monitoring channel morphology in a small forested watershed indicate that pool‐riffles persist through large changes in upstream water and bedload supply and that bed architecture relief is correlated to flow magnitude. A flume experiment consisting of eight runs was conducted to examine the field case in more detail. The experimental design splits the eight runs into four runs of relatively high water and sediment supply and four of relatively low water supply, with no upstream sediment supply. Experimental results corroborate the field‐based measurements of pool‐riffle persistence, which is due to a coupling between downstream width variations, and spatial patterns of flow velocity and bedload transport. More specifically, measurements made during the flume experiments along a prominent pool‐riffle pair indicate that temporal and spatial changes to topography, flow hydraulics, and bed surface sediment texture are more rich and nuanced than existing generalizations offer. For example, clustering analysis completed using self‐organizing maps indicates that sediment sorting between pools and riffles is not simply a binary type response of finer versus coarser described by some characteristic grain size.

Influence of Erodible Beds on Shallow Water Hydrodynamics during Flood Events

Flooding has become the most common environmental hazard, causing casualties and severe economic losses. Mathematical models are a useful tool for flood control, and current computational resources let us simulate flood events with two-dimensional (2D) approaches. An open question is whether bed erosion must be accounted for when it comes to simulating flood events. In this paper we answer this question through numerical simulations using the 2D depth-averaged shallow-water equations. We analyze the effect of mobile beds on the flow patterns during flood events. We focus on channel confluences where water flow and sediment mobilization have a marked 2D behavior. We validate our numerical simulations with laboratory experiments of erodible beds with satisfactory results. Moreover, our sensitivity analysis indicates that the bed roughness model has a great influence on the simulated erosion and deposition patterns. We simulate the sediment transport and its influence on the water flow in a real river confluence during flood events. Our simulations show that the erosion and deposition processes play an important role on the water depth and flow velocity patterns. Accounting for the mobile bed leads to smoother water depth and velocity fields, as abrupt fields for the non-erodible model emerge from the irregular bed topography. Our study highlights the importance of accounting for erosion in the simulation of flood events, and the impact on the water depth and velocity fields.

Flow velocity pattern around trapezoidal piano key side weirs

In general, the side weirs are the structures installed along a channel or river. When the flow depth rises above the weir crest, the overflow passes through these weirs and enters the lateral canal. Nowadays, piano key weirs are considered as an important alternative to labyrinth weirs to modify the weirs encountering with difficulty to pass the maximum flow discharges. The present study investigates the hydrodynamic performance and the effect of the uniformity of velocity field on the resultant kinetic energy in the trapezoidal piano key side weirs with 90° installed laterally in the main channel wall. These weirs are classified as A-Type piano key weirs and two approaches (main: Mode 1 and adverse: Mode 2) were used to investigate the effect of the weirs' placement on their performance. The results showed that for velocity vectors in both modes, on average, the maximum flow discharge through the side weir occurred in the x and y directions (Vx and Vy) at Z*<0.2 and 0.2<Y*<0.7. The results also showed that at the control surface of X* = 1, the maximum values of α occur due to existing the inverse flow and increasing the deflection angle of the velocity vectors. The performance of the weir in Mode 2 was more appropriate Mode 1 due to the lack of weir base at the flow inlet, which is an obstacle for the deflection angle of the velocity vectors.

Impacts of long-term climate change on the groundwater flow dynamics in a regional groundwater system: Case modeling study in Alashan, China

Groundwater flow dynamics plays a crucial role in social development and ecosystem protection. This study investigated the impacts of long-term climate change on the regional groundwater flow in Alashan, China to reveal the spatial variability of groundwater flow response to climate change and the dynamic patterns of both deep and shallow groundwater flow velocity. To this end, the hydrogeologic conditions and climate evolution history were analyzed. Based on these, four future scenarios of long-term climate change were designed, including linearly varying and cyclic changes, and numerical groundwater flow modeling was then conducted to investigate the effects of long-term climate changes on groundwater flow dynamics (including groundwater level and flow velocity). It was found that groundwater level dynamics were notably influenced by climate changes; the time scale and initial change pattern of cyclic climate influenced the amplitude and mean level of groundwater level fluctuations. In addition, our results also revealed that, for a regional groundwater system, climate change impacts on groundwater level had obvious spatial variability. Groundwater level in recharge and discharge areas were sensitive to drying and wetting climates, respectively. Thus, the spatial variability of groundwater level dynamics reflected climate change information. Moreover, groundwater flow velocity dynamics were also affected by climate changes. However, linearly varying and cyclic climates had different influences. Linearly wetting climate generally increased the groundwater flow velocity in recharge and discharge areas, but decreased that in runoff area, whereas cyclic climate induced periodical fluctuation of groundwater flow velocity. The fluctuation period of shallow groundwater flow velocity matched the full climate cycle period, whereas of the deep groundwater flow velocity was only half. This unique behavior of deep groundwater flow velocity is caused by fluctuation of the vertical velocity alternating between positive (upward flow) and negative (downward flow) values. This finding of groundwater flow velocity dynamics contributes to deeper understanding of long-term climate change effects on groundwater flow dynamics.

A numerical simulation study on the sedimentation dredging in Lushui Reservoir, part 2: influence and its back siltation

A well-verified two-dimensional mathematical model for vertical averaged flow was used to calculate the influence on the flow after the sedimentation dredging in Lushui Reservoir. The numerical simulation results shows that the influence of dredging works on the flow in the dredging reach is limited, and the influence is mainly concentrated in the local area near the dredging area, while the influence on the velocity flow pattern and the overall river regime in the main channel of the dredging reach is relatively small.

Duplex Ultrasound Investigation for the Detection of Obstructed Iliocaval Venous Stents

Duplex ultrasound (DUS) is used for routine surveillance of stents in iliocaval veins, but direct visualisation is often challenging. Duplex ultrasound criteria for detecting venous stent obstruction (VSO) have not been defined to date. A nested case control study of 120 patients (42±17 years, 53% women, mean 2.7±1.8 stents) was performed, and the performance of various duplex parameters for detecting VSO (defined as>50% lumen diameter reduction or occlusion) was tested, confirmed by biplane venography or intravascular ultrasound (IVUS). Forty patients with VSO (25 with stent occlusion, 15 with >50% in stent stenosis) were matched to 80 control patients by age, gender and index diagnosis who fulfilled the following criteria: (1) ongoing symptom control (Villalta score<5), (2) good image quality of entire stent segment, (3) spontaneous colour Doppler signal>50% of lumen in entire stent segment, (4) at least two DUS where the baseline DUS was obtained within 24h after successful venous intervention. The best test was the combination of peak flow velocity and flow pattern analysis at the stent inlet. A peak flow velocity >10cm/s and a flow pattern spontaneously modulated by respiration ruled out VSO with a specificity of 93.7% (95% CI 86.0%-97.3%). A peak flow velocity ≤10cm/s or any Doppler flow pattern other than spontaneously modulated by respiration was 92.1% (95% CI 79.2%-97.3%) sensitive to detect VSO. The combination of peak flow velocity and analysis of Doppler flow pattern at the stent inlet is accurate to diagnose or rule out stent occlusion. Indirect criteria should always be combined with direct visualisation of iliocaval stents since those may be less sensitive for detecting stent stenosis.

Numerical simulation of turbulent flow in an eccentric channel

The aim of this work is to perform a numerical simulation of the turbulent flow in an eccentric channel for a Reynolds number ReDh= 7300. The Reynolds number is based on the bulk velocity, UBulk, the hydraulic-diameter, Dh, and the kinematic viscosity, ν. To achieve this goal, a hybrid RANS/LES turbulence model called DES-SST is used. In this formulation, special functions are computed to convert the model from RANS close to the walls to LES in more remote regions. Besides the Reynolds number, the main dimensionless parameter related to the geometry involves the narrow gap between the outer and inner walls of the pipes and their diameters, D and d, respectively. These geometric parameters are related to the eccentricity, e, and the d/D ratio. Both of these parameters were kept constant at 0.80 and 0.50, respectively, throughout the work, as the channel’s length, L=1500 mm. The numerical results are compared with experimental outcomes for a water channel with the same Reynolds number using PIV measurements. The hybrid scheme was able to capture the onset of gap instability, short after the channel’s inlet. Furthermore, the mass flow distribution along the channel and the flow velocity patterns were also successfully predicted by the numerical code. The Strouhal number was found to be in fair agreement with the experimental result. The large-scale structures were found to spread over the whole cross-section. The main frequency produced by the oscillatory motion in the tight gap was seen to be twice as high as that found in the lateral subchannel.

Numerical Simulation of Breakwater Layout in Puger Beach Jember Due to Tidal Wave

Puger Beach is located in the south Coast of Java Island which is directly facing the Indian Ocean. The ease of the ship to sail is influenced by the conditions of water in the port which caused by tides. The elevation of the crest of a breakwater is determined by the maximum high water level, while the depth of the shipping lane / port is determined by the minimum low water level. The purpose of this research is to evaluate the breakwater performance by analyzing the surface water level and flow velocity caused by tidal wave in Puger Beach using Delft3D-Flow. The bathymetry data obtained from BIG (Geospatial Information Agency of Indonesia) were utilized for the simulations. Tidal observation results from the previous study were used to validate the model. Two scenarios of breakwater layout were simulated. Spatial variation of flow velocities in the highest tide, the minimum ebb, and representative time steps for both cases are presented. It is shown that using the modified layout of breakwater, the flow velocities become smaller and more stable than that of the existing layout. Using breakwater in the right and left hand side of estuary, high velocities are able to be reduced. Based on the flow velocity pattern in five observation points and the water level, it is confirmed the modified breakwater layout of is more effective than that of the existing one.

P1323 From a suspicion of pulmonary arterial hypertension to a rare form of Takayasu disease

Abstract A 27-year-old female with a history of glomerulonephritis,with diagnosed systemic lupus and retroperitoneal fibrosis was admitted due to fast worsening dyspnoea(NYHA class IV) over the prior four weeks with suspicion for PA hypertension. In 2015, retroperitoneal fibrosis was diagnosed based on MR examination. With the methylprednisolone treatment a regression of changes was obtained. The patient was chronically treated with prednisone 7.5mg/day and mycophenolate mofetil 2g/d. When admitted to the ward, the patient was in a severe condition, with symptoms of resting dyspnea and blood oxygen saturation up to 80%. A loud systolic murmur was audible over the entire chest. In laboratory tests, the NT-proBNP values (11,000 pg/ml) were significantly elevated, arterial blood gases showed tendency to alkalosis, hypoxemia (PO2 45mmHg)with hypocapnia. Parameters of inflammation were moderately elevated (CRP 25mg/l, WBC 12,000/ul), with normal serum IgG4 concentrations. In TTE, significant dilatation of the right ventricle with left chamber compression were observed. Tricuspid ring dilation with no leaflets coaptation and a severe tricuspid regurgitation (Vmax 5m/s, RVSP 100mmHg) were found. In addition, the critical proximal pulmonary artery (PA) stenosis was revealed (left PA Vmax 3.3m/s, Pmax 42mmHg, right PA Vmax 5.2 m/s, Pmax 110mmHg). Angio-CT confirmed critical proximal constriction of both PAs with a flow channelup to 4 mm. Based on angio-CT and cardiac MR study the inflammatory etiology of stenoses was suspected and an empiric diagnosis of the Takayahu disease of pulmonary arteries was made. The patient was qualified for conservative treatment using prednisone and cyclophosphamide. Over the course of two months,2.8 g of cyclophosphamide were administered intravenously in three cycles with good response to the treatment. It resulted in regression of dyspnea and a improvement in exercise tolerance - to the NYHA class II, normalization of saturation. Laboratory tests showed reduction of NT-proBNP (1300 pg/ml). Control TTE revealed reduction in the size of the right ventricle and regression of PAs stenoses (left PA 11mm, right PA 7mm), also reduction of systolic flow gradients (left PA Vmax 3.1 m / s, Pmax 39 mmHg, right PA 4.1 m/s, Pmax 68 mmHg). Because of the significant improvement in patient’s condition,it was decided to continue the treatment. Legend for the Fig.1 A angio-CT, critical proximal constriction of both PA B TTE, parasternal short axis view, imflammatory infiltration C TTE, continuous wave doppler, flow velocity pattern in the PA stenosis D TTE PLAX, dilatation of the right ventricle with left chamber compression fig. 1 Abstract P1323 Figure. Fig.1 artety pulmonary stenosis

Design of Air Distribution System for Operation Theatre Using Flow Visualization Techniques to Improve Flow Characteristics

Operation Theatre (OT) is the most important area where precise controlled on indoor air quality is required because it is directly related to patient health and its recovery period. This work aims to study and visualize the airflow distribution of conventional flat air diffuser ventilation system and newly designed angular air ventilation system in OT. Angular Air Distribution (AAD) system is designed in such way that, conditioned air is throw in OT with some angle so it can cover the maximum area of OT with laminar flow and minimum installation area. The performance of angular air distribution (AAD) system with varying inlet diffuser angle, constant 0.4m/s inlet velocity and air flow pattern are investigated with the help of numerical simulation and experimental setup of prototype OT model. Detail experimental investigation is done on a prototype with the help of a smoke test and camera target method (CTM). Both numerical and experimental results showed a similar pattern of air distribution for the various design configurations.