scholarly journals 3D CFD Analysis of Natural Ventilation in Reduced Scale Model of Compost Bedded Pack Barn for Dairy Cows

2020 ◽  
Vol 10 (22) ◽  
pp. 8112
Author(s):  
Flávio A. Damasceno ◽  
Joseph L. Taraba ◽  
George B. Day ◽  
Felipe A. O. Vega ◽  
Keller S. O. Rocha ◽  
...  
Keyword(s):  
Wind Direction ◽  
Natural Ventilation ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Housing System ◽  
Scale Model ◽  
Alternative Housing ◽  
East Wind ◽  
Naturally Ventilated Buildings ◽  
The Impact

Compost bedded pack (CBP) barns have been receiving increased attention as an alternative housing system for dairy cattle. To create a satisfactory environment within CBP barns that promotes a good composting process, an adequate air movement and minimal temperature fluctuations throughout the building are required. Therefore, a study based on compost barn structure model employing techniques of dimensional analysis for naturally ventilated buildings was developed. Three-dimensional computational fluid dynamic (CFD) simulations of compost barns with different ridge designs and wind direction, along with the visual demonstration of the impact on airflow through structure were performed. The results showed that the barn ventilation CFD model and simulations were in good agreement with the experimental measurements, predicting the airflow through the CBP barns structure for alternative roof ridge types adequately. The results also indicate that the best roof configuration in the winter was the open ridge with chimney for a west to east wind direction.

scholarly journals Thin Solid Film Electrolyte and Its Impact on Electrode Polarization in Solid Oxide Fuel Cells Studied by Three-Dimensional Microstructure-Scale Numerical Simulation

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5127
Author(s):  
Tomasz A. Prokop ◽  
Grzegorz Brus ◽  
Shinji Kimijima ◽  
Janusz S. Szmyd
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Three Dimensional ◽  
Reaction Rates ◽  
Solid Oxide ◽  
Scale Model ◽  
Electrode Polarization ◽  
Computational Domain ◽  
Oxide Fuel ◽  
The Impact

In this work, a three-dimensional microstructure-scale model of a Solid Oxide Fuel Cell’s Positive-Electrolyte-Negative assembly is applied for the purpose of investigating the impact of decreasing the electrolyte thickness on the magnitude, and the composition of electrochemical losses generated within the cell. Focused-Ion-Beam Scanning Electron Microscopy reconstructions are used to construct a computational domain, in which charge transport equations are solved. Butler–Volmer model is used to compute local reaction rates, and empirical relationships are used to obtain local conductivities. The results point towards three-dimensional nature of transport phenomena in thin electrolytes, and electrode-electrolyte interfaces.

On the Role of Leading-Edge Bumps in the Control of Stall Onset in Axial Fan Blades

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Alessandro Corsini ◽  
Giovanni Delibra ◽  
Anthony G. Sheard
Keyword(s):  
Numerical Study ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Leading Edge ◽  
Suction Side ◽  
Axial Fan ◽  
Early Recovery ◽  
Viscosity Models ◽  
Flow Mechanisms ◽  
The Impact

Taking a lead from the humpback whale flukes, characterized by a series of bumps that result in a sinusoidal-like leading edge, this paper reports on a three-dimensional numerical study of sinusoidal leading edges on cambered airfoil profiles. The turbulent flow around the cambered airfoil with the sinusoidal leading edge was computed at different angles of attack with the open source solver OpenFOAM, using two different eddy viscosity models integrated to the wall. The reported research focused on the effects of the modified leading edge in terms of lift-to-drag performance and the influence of camber on such parameters. For these reasons a comparison with a symmetric airfoil is provided. The research was primarily concerned with the elucidation of the fluid flow mechanisms induced by the bumps and the impact of those mechanisms on airfoil performance, on both symmetric and cambered profiles. The bumps on the leading edge influenced the aerodynamic performance of the airfoil, and the lift curves were found to feature an early recovery in post-stall for the symmetric profile with an additional gain in lift for the cambered profile. The bumps drove the fluid dynamic on the suction side of the airfoil, which in turn resulted in the capability to control the separation at the trailing edge in coincidence with the peak of the sinusoid at the leading edge.

Anti-Slosh Effectiveness of Baffles and Braking Performance of a Partly-Filled Tank Truck

2014 ◽  
Vol 541-542 ◽  
pp. 674-683
Author(s):  
Fan Yang ◽  
G. Yan ◽  
S. Rakheja
Keyword(s):  
Fluid Dynamic ◽  
Fluid Motion ◽  
Three Dimensional ◽  
Scale Model ◽  
Fluid Structure Interactions ◽  
Tank Truck ◽  
Plane Model ◽  
Braking Performance ◽  
Straight Line ◽  
Spectral Components

The liquid cargo movement within a partly-filled tank truck affects its braking, roll dynamics and directional performance in an adverse manner. In this study, the braking performance of a partly-filled tank truck equipped with different baffles designs is investigated considering dynamic fluid-structure interactions. The validity of the computational fluid dynamic model is examined through laboratory tests conducted on a scale model tank with and without baffles. The measured responses to harmonic excitations revealed three-dimensional nature of the fluid motion and couplings between the lateral and longitudinal fluid slosh. Several spectral components were observed for the transient slosh forces, which could be associated with the excitation, resonance, and beat frequencies. A dynamic pitch plane model of a Tridem truck incorporating three-dimensional fluid slosh dynamics is subsequently developed to analyze the fluid-vehicle interactions under straight-line braking maneuvers. The results show that the vehicle responses are highly influenced by the slosh-induced force and moment.

scholarly journals The total cavopulmonary connection resistance: a significant impact on single ventricle hemodynamics at rest and exercise

2008 ◽  
Vol 295 (6) ◽  
pp. H2427-H2435 ◽  
Author(s):  
Kartik S. Sundareswaran ◽  
Kerem Pekkan ◽  
Lakshmi P. Dasi ◽  
Kevin Whitehead ◽  
Shiva Sharma ◽  
...  
Keyword(s):  
Heart Rate ◽  
Single Ventricle ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Lumped Parameter Model ◽  
Total Cavopulmonary Connection ◽  
Dynamic Simulations ◽  
Lumped Parameter ◽  
The Impact ◽  
Cavopulmonary Connection

Little is known about the impact of the total cavopulmonary connection (TCPC) on resting and exercise hemodynamics in a single ventricle (SV) circulation. The aim of this study was to elucidate this mechanism using a lumped parameter model of the SV circulation. Pulmonary vascular resistance (1.96 ± 0.80 WU) and systemic vascular resistances (18.4 ± 7.2 WU) were obtained from catheterization data on 40 patients with a TCPC. TCPC resistances (0.39 ± 0.26 WU) were established using computational fluid dynamic simulations conducted on anatomically accurate three-dimensional models reconstructed from MRI ( n = 16). These parameters were used in a lumped parameter model of the SV circulation to investigate the impact of TCPC resistance on SV hemodynamics under resting and exercise conditions. A biventricular model was used for comparison. For a biventricular circulation, the cardiac output (CO) dependence on TCPC resistance was negligible (sensitivity = −0.064 l·min−1·WU−1) but not for the SV circulation (sensitivity = −0.88 l·min−1·WU−1). The capacity to increase CO with heart rate was also severely reduced for the SV. At a simulated heart rate of 150 beats/min, the SV patient with the highest resistance (1.08 WU) had a significantly lower increase in CO (20.5%) compared with the SV patient with the lowest resistance (50%) and normal circulation (119%). This was due to the increased afterload (+35%) and decreased preload (−12%) associated with the SV circulation. In conclusion, TCPC resistance has a significant impact on resting hemodynamics and the exercise capacity of patients with a SV physiology.

Particle Image Velocimetry Measurement and Computational Fluid Dynamic Simulations of the Unsteady Flow Within a Rotating Disk Cavity

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Xiang Luo ◽  
Dongdong Liu ◽  
Hongwei Wu ◽  
Zhi Tao
Keyword(s):  
Particle Image Velocimetry ◽  
Computational Fluid Dynamic ◽  
Particle Image ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Rotating Disk ◽  
Turbine Rotor ◽  
Dynamic Simulations ◽  
Image Velocimetry ◽  
The Impact

In this article a combined experimental and numerical investigation of the unsteady mixing flow of the ingestion gas and rim sealing air inside a rotating disk cavity was carried out. A new test rig was set up, and the experiments were conducted on a 1.5-stage turbine rotor disk and included pressure measurements. The flow structure of the mixing region of the ingestion gas and sealing air in cavity was measured using the particle image velocimetry (PIV) technique. To complement the experimental investigation and to aid in understanding the flow mechanism within the cavity, a three-dimensional (3D) unsteady computational fluid dynamic (CFD) analysis was undertaken. Both simulated and experimental results indicated that near the rotating disk, (i) a large amount of the ingestion gas will turn around and flow out the cavity due to the impact of the centrifugal force and the Coriolis force, (ii) a small amount of ingestion gas will mix transiently with the sealing air inside the cavity, whereas near the static disk, (iii) the ingestion gas will flow into the cavity along the static wall and mix with the sealing air.

scholarly journals THREE-DIMENSIONAL COMPUTATIONAL PREDICTION OF VORTEX SEPARATION PHENOMENON INSIDE THE RANQUE-HILSCH VORTEX TUBE

Aviation ◽  
2016 ◽  
Vol 20 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Seyed Ehsan RAFIEE ◽  
Mohammad Bagher Mohammad SADEGHIAZAD
Keyword(s):  
Turbulence Model ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Computational Prediction ◽  
Separation Process ◽  
Counter Flow ◽  
Vortex Separation ◽  
The Impact ◽  
Air Separator

The air separators are used to provide safe, clean and appropriate air to the helicopter’s engine. In this operational study, the separation process inside a Ranque-Hilsch air separator cleaning system has been investigated to analyze the impact of choosing the appropriate turbulence model for predicting the separation process inside the air separator. This research is directed towards presenting a computational fluid dynamic explanation performed on a counter-flow air separator using air at different magnitudes of air flow fraction and applying different turbulence models. In a numerical investigation of counter-flow air separator, air has been chosen and its vortex separation phe- nomenon has been analyzed as a function of flow fraction. Furthermore, a numerical analysis to compare the outputs of a seven equation RSM turbulence model applied for the study of vortex separation of a counter-flow air separator with some two-equation turbulence methods, namely, k-ε and k-ω model as well as LES has been presented. All of the turbulence numerical methods are seen to present and predict the same flow pattern inside an air separator, but, with various details. The results show that among the tested methods the RSM creates the most accurate separation pattern. The numerical results are validated by some available experimental data with good agreement.

The Impact of Assimilating SSM/I and QuikSCAT Satellite Winds on Hurricane Isidore Simulations

2007 ◽  
Vol 135 (2) ◽  
pp. 549-566 ◽  
Author(s):  
Shu-Hua Chen
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Mesoscale Model ◽  
Three Dimensional ◽  
Storm Track ◽  
Initial Position ◽  
Wind Speeds ◽  
The Impact ◽  
Quikscat Winds

Abstract Three observational datasets of Hurricane Isidore (in 2002) were analyzed and compared: the Special Sensor Microwave Imager (SSM/I), the Quick Scatterometer (QuikSCAT) winds, and dropsonde winds. SSM/I and QuikSCAT winds were on average about 1.9 and 0.3 m s−1 stronger, respectively, than dropsonde winds. With more than 20 000 points of data, SSM/I wind speed was about 2.2 m s−1 stronger than QuikSCAT. Comparison of the wind direction observed by QuikSCAT with those from the dropsondes showed that the quality of QuikSCAT data is good. The effect of assimilating SSM/I wind speeds and/or QuikSCAT wind vectors for the analysis of Hurricane Isidore was assessed using the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5) and its three-dimensional variational data assimilation system. For the Hurricane Isidore case study, it was found that the assimilation of either satellite winds strengthened the cyclonic circulation in the analysis. However, the increment of the QuikSCAT wind analysis is more complicated than that from the SSM/I analysis due to the correction of the storm location, a positive result from the assimilation of wind vectors. The increase in low-level wind speeds enhanced the air–sea interaction processes and improved the simulated intensity for Isidore. In addition, the storm structure was better simulated. Assimilation of QuikSCAT wind vectors clearly improved simulation of the storm track, in particular during the later period of the simulation, but lack of information about the wind direction from SSM/I data prevented it from having much of an effect. Assessing the assimilation of QuikSCAT wind speed versus wind vector data confirmed this hypothesis. The track improvement partially resulted from the relocation of the storm’s initial position after assimilation of the wind vectors. For this case study, it was found that the assimilation of SSM/I or QuikSCAT data had the greatest impact on the Hurricane Isidore simulation during the first 2 days.

scholarly journals Research on the Impact of Wind Angles on the Residential Building Energy Consumption

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Zou Huifen ◽  
Yang Fuhua ◽  
Zhang Qian
Keyword(s):  
Energy Consumption ◽  
Heat Loss ◽  
Indoor Air ◽  
Wind Direction ◽  
Natural Ventilation ◽  
Building Energy ◽  
Simulation Software ◽  
Outdoor Environment ◽  
Building Energy Consumption ◽  
The Impact

Wind angles affect building’s natural ventilation and also energy consumption of the building. In winter, the wind direction in the outdoor environment will affect heat loss of the building, while in summer the change of wind direction and speed in the outdoor environment will affect the building’s ventilation and indoor air circulation. So, making a good deal with the issue of the angle between local buildings and the dominant wind direction can effectively solve the winter and summer ventilation problems. Thereby, it can enhance the comfort of residential person, improve indoor air quality, solve heat gain and heat loss problems in winter and summer in the severely cold and cold regions, and reduce building energy consumption. The simulation software CFD and energy simulation software are used in the paper. South direction of the building is the prototype of the simulation. The angle between the direction of the building and the outdoor environment wind is changed sequentially. Energy consumption under different wind angle conditions is compared with each other. Combined with natural ventilation under various wind angles, the paper gives the best recommended solution of building direction in Shenyang.

scholarly journals Parallel Computation of EM Backscattering from Large Three-Dimensional Sea Surface with CUDA

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3656 ◽  
Author(s):  
Longxiang Linghu ◽  
Jiaji Wu ◽  
Zhensen Wu ◽  
Xiaobing Wang
Keyword(s):  
Parallel Computation ◽  
Graphics Processing Units ◽  
Data Transfer ◽  
Three Dimensional ◽  
Block Size ◽  
Sea Surface ◽  
Scale Model ◽  
Specular Scattering ◽  
Coalesced Memory ◽  
The Impact

An efficient parallel computation using graphics processing units (GPUs) is developed for studying the electromagnetic (EM) backscattering characteristics from a large three-dimensional sea surface. A slope-deterministic composite scattering model (SDCSM), which combines the quasi-specular scattering of Kirchhoff Approximation (KA) and Bragg scattering of the two-scale model (TSM), is utilized to calculate the normalized radar cross section (NRCS in dB) of the sea surface. However, with the improvement of the radar resolution, there will be millions of triangular facets on the large sea surface which make the computation of NRCS time-consuming and inefficient. In this paper, the feasibility of using NVIDIA Tesla K80 GPU with four compute unified device architecture (CUDA) optimization strategies to improve the calculation efficiency of EM backscattering from a large sea surface is verified. The whole GPU-accelerated SDCSM calculation takes full advantage of coalesced memory access, constant memory, fast math compiler options, and asynchronous data transfer. The impact of block size and the number of registers per thread is analyzed to further improve the computation speed. A significant speedup of 748.26x can be obtained utilizing a single GPU for the GPU-based SDCSM implemented compared with the CPU-based counterpart performing on the Intel(R) Core(TM) i5-3450.

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