scholarly journals Feasibility of Computational Fluid Dynamics for Evaluating the Intraventricular Hemodynamics in Single Right Ventricle Based on Echocardiographic Images

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Li-Jun Chen ◽  
Zhi-Rong Tong ◽  
Qian Wang ◽  
Yu-Qi Zhang ◽  
Jin-Long Liu
Keyword(s):  
Fluid Dynamics ◽  
Heart Failure ◽  
Computational Fluid Dynamics ◽  
Right Ventricle ◽  
Three Dimensional ◽  
Cfd Modeling ◽  
Flow Models ◽  
Echocardiographic Image ◽  
Intraventricular Flow ◽  
And Function

This study introduced a combined computational fluid dynamics (CFD) and echocardiography methodology to simulate blood flow in the single right ventricle (SRV) and normal ventricles to study the intraventricular flow. Derived from echocardiographic image loops, CFD-based three-dimensional (3D) flow models of normal subject’s left ventricle (LV) and right ventricle (RV) and SRV with and without heart failure at three characteristic diastolic statuses were reconstructed. The CFD derived morphological and functional measurements in normal ventricles and the SRV were validated with echocardiography. The vortex in the normal ventricles and the SRV were studied. The morphological and functional measurements derived from CFD modeling and echocardiography were comparable, and both methods demonstrated the larger volume and higher spherical index in the SRV, in particular the SRV with heart failure. All the vortices in the SRV were smaller than those in the normal control subject’s LV and RV, notably with heart failure. Unlike normal LV and RV, no vortex ring was observed in the SRV. Echocardiography-based CFD demonstrated the feasibility of quantifying ventricular morphology and function; in addition, CFD can detect the abnormal flow pattern (smaller or obliterated vortices) in the SRV when compared with normal ventricles.

Computational Fluid Dynamics Based Mixing Prediction for Tilt Pad Journal Bearing TEHD Modeling—Part II: Implementation With Machine Learning

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Jongin Yang ◽  
Alan Palazzolo
Keyword(s):  
Machine Learning ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Leading Edge ◽  
Cfd Modeling ◽  
Inlet Temperature ◽  
Training Set ◽  
Simplified Approach ◽  
Flow Mixing

Abstract Reynolds based thermo-elasto-hydrodynamic (TEHD) simulations of tilting pad journal bearings (TPJBs) generally provide accurate results; however, the uncertainty of the pad’s leading edge thermal boundary conditions causes uncertainty of the results. The highly complex thermal-flow mixing action between pads (BPs) results from the oil supply nozzle jets and geometric features. The conventional Reynolds approach employs mixing coefficients (MCs), estimated from experience, to approximate a uniform inlet temperature for each pad. Part I utilized complex computational fluid dynamics (CFD) flow modeling to illustrate that temperature distributions at the pad inlets may deviate strongly from being uniform. The present work retains the uniform MC model but obtains the MC from detailed three-dimensional CFD modeling and machine learning, which could be extended to the radially and axially varying MC case. The steps for implementing an artificial neural network (ANN) approach for MC regression are provided as follows: (1) utilize a design of experiment step for obtaining an adaptable training set, (2) conduct CFD simulations on the BP to obtain the outputs of the training set, (3) apply an ANN learning process by Levenverg–Mardquart backpropagation with the Bayesian regularization, and (4) couple the ANN MC results with conventional TEHD Reynolds models. An approximate log fitting method provides a simplified approach for MC regression. The effectiveness of the Reynolds TEHD TPJB model with ANN regression-based MC distributions is confirmed by comparison with CFD based TEHD TPJB model results. The method obtains an accuracy nearly the same as the complete CFD model, but with the computational economy of a Reynolds approach.

Extent, capacity and possibilities of computational fluid dynamics as a design tool for pump intakes: a review

2018 ◽  
Vol 18 (5) ◽  
pp. 1518-1530 ◽  
Author(s):  
Jie Zhang ◽  
Tien Yee
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Design Tool ◽  
Cfd Modeling ◽  
Cfd Simulations ◽  
Pump Station ◽  
Computational Fluid Dynamics Cfd ◽  
Future Direction ◽  
Computational Resources

Abstract Flow near pump intakes is three-dimensional in nature, and is affected by many factors such as the geometry of the intake bay, uniformity of approach flow, critical submergence, placements and operation combinations of pumps and so on. In the last three decades, advancement of numerical techniques coupled with the increase in computational resources made it possible to conduct computational fluid dynamics (CFD) simulations on pump intakes. This article reviews different aspects involved in CFD modeling of pump station intakes, outlines the challenges faced by current CFD modelers, and provides an attempt to forecast future direction of CFD modeling of pump intakes.

scholarly journals The effect of using winglets to enhance the performance of swept blades of a horizontal axis wind turbine

2019 ◽  
Vol 11 (9) ◽  
pp. 168781401987831 ◽  
Author(s):  
Mohamed G Khalafallah ◽  
Abdelnaby M Ahmed ◽  
Mohamed K Emam
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Twist Angle ◽  
Three Dimensional ◽  
Horizontal Axis ◽  
Cfd Modeling ◽  
Speed Ratio ◽  
Computational Domain ◽  
Horizontal Axis Wind Turbine

One of the recent methods to improve the performance of horizontal axis wind turbine is to attach a winglet at the tip of the blade of these turbines. Winglets reduce the effect of vortex flow at the blade tip and thus improve the performance of the blade. This article presents a parametric study using the computational fluid dynamics (CFD) modeling to investigate the capability of a winglet to increase the turbine power of swept blades as well as straight blades of a horizontal axis wind turbine. The effects of winglet direction, cant angle, and twist angle are studied for two winglet orientations: upstream and downstream directions. The numerical simulation was performed using ANSYS Fluent computational fluid dynamics code. A three-dimensional computational domain, cylindrical rotationally periodic, was used in the computations. The k-ω shear-stress transport turbulence model was adopted to demonstrate turbulence in the flow. Results show that horizontal axis wind turbine with winglet and sweep could enhance more power compared to their equivalent straight or swept blade. The best improvement in the coefficient of power is 4.39% at design tip speed ratio. This is achieved for downstream swept blades with winglets pointing in the upstream direction and having cant and twist angles of 40° and 10°, respectively.

scholarly journals Novel areas and future trends of computational fluid dynamics software applications in chemical engineering

2006 ◽  
Vol 12 (4) ◽  
pp. 213-219
Author(s):  
O. Faltsi ◽  
S.D. Vlaev ◽  
D. Sofialidis ◽  
J. Kirpitsas
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Single Phase ◽  
Chemical Engineering ◽  
Cfd Modeling ◽  
Process Equipment ◽  
Mixing Efficiency ◽  
Flow Sheet ◽  
Future Trends ◽  
Flow Models

The paper presents a brief overview of advanced novel applications and future trends of Computational Fluid Dynamics software in Chemical Engineering. Among the cases of major importance, single phase turbulent flow, as well as multiphase flow models are reviewed. Referring to single phase flows, the LES and RANS approaches are described and illustrated. The RANS approach is revealed as the most popular and inexpensive method for the analysis and solving of technical tasks. The paper reports on two recent modeling applications, namely, the CFD facilitated design of a new mixing impeller and the CFD characterization of impeller mixing efficiency. Multiphase models of increased sophistication describing solid, liquid and gas flows with simultaneous mass transfer between the phases are summarized with emphasis on their applications to describe evaporation, condensation, as well as chemical reactions in process equipment such as distillation columns and fluidized beds. The future trends and directions in Computer Aided methods for the analysis of Chemical Engineering processes incorporate developments, such as the integration of various pieces of software including flow sheet modeling CFD modeling and complex reaction and thermodynamic models.

scholarly journals Computational Fluid Dynamics Analysis of Alternative Ventilation Schemes in Cage-Free Poultry Housing

Animals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2352
Author(s):  
Long Chen ◽  
Eileen E. Fabian-Wheeler ◽  
John M. Cimbala ◽  
Dan Hofstetter ◽  
Paul Patterson
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Ventilation System ◽  
Airflow Obstruction ◽  
Three Dimensional ◽  
Ventilation Rate ◽  
Full Scale ◽  
Cold Weather ◽  
Cfd Modeling ◽  
Computational Fluid Dynamics Analysis

This work investigated alternative ventilation schemes to help define a proper ventilation system design in cage-free hen houses with the goal of assuring bird welfare through comfortable conditions. Computational fluid dynamics (CFD) modeling was employed to simulate indoor and outdoor airflows to quantify the effectiveness of ventilation systems in maintaining suitable and uniform living conditions at the hen level. Four three-dimensional CFD models were developed based on a full-scale floor-raised layer house, corresponding to ventilation schemes of the standard top-wall inlet, sidewall exhaust, and three alternatives: mid-wall inlet, ceiling exhaust; mid-wall inlet, ridge exhaust; and mid-wall inlet, attic exhaust with potential for pre-treatment of exhaust air. In a sophisticated and powerful achievement of the analysis, 2365 birds were individually modeled with simplified bird-shapes to represent a realistic number, body heat, and airflow obstruction of hens housed. The simulated ventilation rate for the layer house models was 1.9–2.0 m3/s (4100 ft3/min) in the desired range for cold weather (0 °C). Simulation results and subsequent analyses demonstrated that these alternative models had the capacity to create satisfactory comfortable temperature and air velocity at the hen level. A full-scale CFD model with individual hen models presented robustness in evaluating bird welfare conditions.

scholarly journals Computational Fluid Dynamics Modeling of Rotating Annular VUV/UV Photoreactor for Water Treatment

Processes ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 79
Author(s):  
Minghan Luo ◽  
Wenjie Xu ◽  
Xiaorong Kang ◽  
Keqiang Ding ◽  
Taeseop Jeong
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Water Treatment ◽  
Cfd Modeling ◽  
Flow Mode ◽  
Oh Radicals ◽  
Dynamics Modeling ◽  
Rotational Movement ◽  
Contaminant Degradation ◽  
Wide Range

The ultraviolet photochemical degradation process is widely recognized as a low-cost, environmentally friendly, and sustainable technology for water treatment. This study integrated computational fluid dynamics (CFD) and a photoreactive kinetic model to investigate the effects of flow characteristics on the contaminant degradation performance of a rotating annular photoreactor with a vacuum-UV (VUV)/UV process performed in continuous flow mode. The results demonstrated that the introduced fluid remained in intensive rotational movement inside the reactor for a wide range of inflow rates, and the rotational movement was enhanced with increasing influent speed within the studied velocity range. The CFD modeling results were consistent with the experimental abatement of methylene blue (MB), although the model slightly overestimated MB degradation because it did not fully account for the consumption of OH radicals from byproducts generated in the MB decomposition processes. The OH radical generation and contaminant degradation efficiency of the VUV/UV process showed strong correlation with the mixing level in a photoreactor, which confirmed the promising potential of the developed rotating annular VUV reactor in water treatment.

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