scholarly journals Experimental Validation Benchmark Data for Computational Fluid Dynamics of Transient Convection From Forced to Natural With Flow Reversal on a Vertical Flat Plate

2016 ◽  
Vol 1 (3) ◽  
Author(s):  
Blake W. Lance ◽  
Barton L. Smith
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Velocity Profiles ◽  
Flow Reversal ◽  
System Response ◽  
Heated Plate ◽  
Cfd Validation ◽  
Validation Data ◽  
Benchmark Data ◽  
Extra Effort

Transient convection has been investigated experimentally for the purpose of providing computational fluid dynamics (CFD) validation benchmark data. A specialized facility for validation benchmark experiments called the rotatable buoyancy tunnel (RoBuT) was used to acquire thermal and velocity measurements of flow over a smooth, vertical heated plate in air. The initial condition was forced convection downward with subsequent transition to mixed convection, ending with natural convection upward after a flow reversal. Data acquisition through the transient was repeated for ensemble-averaged results. With simple flow geometry, validation data were acquired at the benchmark level. All boundary conditions (BCs) were measured and their uncertainties quantified. Temperature profiles on all the four walls and the inlet were measured, as well as as-built test section geometry. Inlet velocity profiles and turbulence levels were quantified using particle image velocimetry (PIV). System response quantities (SRQs) were measured for comparison with CFD outputs and include velocity profiles, wall heat flux, and wall shear stress. Extra effort was invested in documenting and preserving the validation data. Details about the experimental facility, instrumentation, experimental procedure, materials, BCs, and SRQs are made available through this paper. The latter two are available for download while other details are included in this work.

scholarly journals Experimental Validation Data for Computational Fluid Dynamics of Forced Convection on a Vertical Flat Plate

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Jeff R. Harris ◽  
Blake W. Lance ◽  
Barton L. Smith
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Forced Convection ◽  
Vertical Plate ◽  
Navier Stokes ◽  
Validation Dataset ◽  
System Response ◽  
Cfd Validation ◽  
Validation Data ◽  
Computational Fluid Dynamics Cfd

A computational fluid dynamics (CFD) validation dataset for turbulent forced convection on a vertical plate is presented. The design of the apparatus is based on recent validation literature and provides a means to simultaneously measure boundary conditions (BCs) and system response quantities (SRQs). All important inflow quantities for Reynolds-Averaged Navier-Stokes (RANS). CFD are also measured. Data are acquired at two heating conditions and cover the range 40,000 < Rex < 300,000, 357 <  Reδ2 < 813, and 0.02 < Gr/Re2 < 0.232.

Experimental Validation Benchmark Data for Computational Fluid Dynamics of Mixed Convection on a Vertical Flat Plate

2016 ◽  
Vol 1 (2) ◽  
Author(s):  
Blake W. Lance ◽  
Jeff R. Harris ◽  
Barton L. Smith
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Mixed Convection ◽  
Turbulent Flows ◽  
Velocity Profiles ◽  
Heated Wall ◽  
Validation Data ◽  
Cfd Models ◽  
Fluid Properties ◽  
High Level

Model validation for computational fluid dynamics (CFD), where experimental data and model outputs are compared, is a key tool for assessing model uncertainty. In this work, mixed convection was studied experimentally for the purpose of providing validation data for CFD models with a high level of completeness. Experiments were performed in a facility built specifically for validation with a vertical, flat, heated wall. Data were acquired for both buoyancy-aided and buoyancy-opposed turbulent flows. Measured boundary conditions (BCs) include as-built geometry, inflow mean and fluctuating velocity profiles, and inflow and wall temperatures. Additionally, room air temperature, pressure, and relative humidity were measured to provide fluid properties. Measured system responses inside the flow domain include mean and fluctuating velocity profiles, temperature profiles, wall heat flux, and wall shear stress. All of these data are described in detail and provided in tabulated format.

Abstract 20526: Computational Fluid Dynamics in Partial Mechanical Circulatory Support: Implications for Patient Care

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Sasan Partovi ◽  
Christoph Karmonik ◽  
Fabian Rengier ◽  
Matthias Mueller-Eschner ◽  
Hagen Meredig ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Heart Failure ◽  
Computational Fluid Dynamics ◽  
Mechanical Circulatory Support ◽  
Cardiac Cycle ◽  
Heart Function ◽  
Innominate Artery ◽  
Flow Patterns ◽  
Flow Reversal ◽  
Circulatory Support

Introduction: Partial mechanical circulatory support (pMCS) is used for the therapy of heart failure. The CircuLite® Pump has been introduced clinically with its inflow cannula connected to the left atrium and the outflow cannula to the right subclavian artery. Aim of our study was to visualize and quantify flow patterns using computational fluid dynamics (CFD) in CT angiography (CTA). Methods: Two heart failure patients with pMCS were imaged with ECG-gated CTA and echocardiography. CFD was performed in 3D derived from CTA using flow boundary conditions measured with ultrasound. Flow was visualized using velocity vectors of blood flow. Average velocity was calculated at 10 time points during cardiac cycle in the aorta and the innominate. Wall shear stress (WSS) was visualized on the wall of the digital model. Results: Flow reversal was observed in mid-systole for both cases distal from the origin of the innominate artery in both cases due to asynchrony of the constant flow of the device with the pulsatile flow of the heart (fig.). Maximum velocity of this back flow was 0.39 m/s in case 1 and 0.2 m/s in case 2. Therefore, further distal in the innominate artery, a region of slow and stagnant flow with low WSS at the artery wall was observed which changed during cardiac cycle. Conclusions: CFD analysis revealed an asynchronous behavior in the inducted flow patterns during systole. Further design should allow for synchronization with the native heart function. Figure: On top flow during systole for both cases (case 1 on left), below flow during diastole. WSS is shown in pseudo-color representation with red indicating high values. Flow is visualized by arrows. During systole, a region of low WSS (blue) exists in the innominate artery which is absent during systole indicating flow reversal at this location. Bottom panel: Velocity in inferior-superior direction during cardiac cycle for both cases. Red lines demonstrates change of direction of flow in the innominate during systole.

Air Ingress Analysis: Computational Fluid Dynamics Models

2010 ◽  
Author(s):  
Chang H. Oh ◽  
Eung S. Kim
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Temperature ◽  
Fluid Dynamic ◽  
Department Of Energy ◽  
Validation Data ◽  
The Core ◽  
Air Ingress ◽  
Dynamics Models ◽  
Very High

Idaho National Laboratory (INL), under the auspices of the U.S. Department of Energy (DOE), is performing research and development that focuses on key phenomena important during potential scenarios that may occur in very high temperature reactors (VHTRs). Phenomena identification and ranking studies to date have ranked an air ingress event, following on the heels of a VHTR depressurization, as important with regard to core safety. Consequently, the development of advanced air-ingress-related models and verification and validation data are a very high priority. Following a loss of coolant and system depressurization incident, air will enter the core of the High Temperature Gas Cooled Reactor through the break, possibly causing oxidation of the core and reflector graphite structure. Simple core and plant models indicate that, under certain circumstances, the oxidation may proceed at an elevated rate with additional heat generated from the oxidation reaction itself. Under postulated conditions of fluid flow and temperature, excessive degradation of lower plenum graphite can lead to a loss of structural support. Excessive oxidation of core graphite can also lead to a release of fission products into the confinement, which could be detrimental to reactor safety. Computational fluid dynamics models developed in this study will improve our understanding of this phenomenon. This paper presents two-dimensional (2-D) and three-dimensional (3-D) computational fluid dynamic (CFD) results for the quantitative assessment of the air ingress phenomena. A portion of the results from density-driven stratified flow in the inlet pipe will be compared with the experimental results.

Three-Dimensional Computational Fluid Dynamics Prediction of Turbocharger Centrifugal Compression System Instabilities

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Rick Dehner ◽  
Ahmet Selamet
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Rate ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Rotating Stall ◽  
Flow Reversal ◽  
Constant Speed ◽  
Local Flow ◽  
Stall Cells

The present work combines experimental measurements and unsteady, three-dimensional computational fluid dynamics predictions to gain further insight into the complex flow-field within an automotive turbocharger centrifugal compressor. Flow separation from the suction surface of the main impeller blades first occurs in the mid-flow range, resulting in local flow reversal near the periphery, with the severity increasing with decreasing flow rate. This flow reversal improves leading-edge incidence over the remainder of the annulus, due to (a) reduction of cross-sectional area of forward flow, which increases the axial velocity, and (b) prewhirl in the direction of impeller rotation, as a portion of the tangential velocity of the reversed flow is maintained when it mixes with the core flow and transitions to the forward direction. As the compressor operating point enters the region where the slope of the constant speed compressor characteristic (pressure ratio versus mass flow rate) becomes positive, rotating stall cells appear near the shroud side diffuser wall. The angular propagation speed of the diffuser rotating stall cells is approximately 20% of the shaft speed, generating pressure fluctuations near 20% and 50% of the shaft frequency, which were also experimentally observed. For the present compressor and rotational speed, flow losses associated with diffuser rotating stall are likely the key contributor to increasing the slope of the constant speed compressor performance curve to a positive value, promoting the conditions required for surge instabilities. The present mild surge predictions agree well with the measurements, reproducing the amplitude and period of compressor outlet pressure fluctuations.

CFD Validation for a Marine Propeller Using an Unstructured Mesh Based RANS Method

2003 ◽  
Author(s):  
Shin Hyung Rhee ◽  
Shitalkumar Joshi
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Tip Vortex ◽  
Computational Results ◽  
Marine Propeller ◽  
Experimental Conditions ◽  
Cfd Validation ◽  
Local Flow ◽  
Thrust And Torque

Results of computational fluid dynamics validation for flow around a marine propeller are presented. Computations were performed for various advance ratios following experimental conditions. The objectives of the study are to propose and verify a hybrid mesh generation strategy, and to validate computational results against experimental data with advanced computational fluid dynamics tools. Computational results for both global and local flow quantities are discussed and compared with experimental data. The predicted thrust and torque are in good agreement with the measured values. The pressure distribution and pathlines on and around the blade surface well reproduce the physics of highly skewed marine propeller flow with tip vortex. The circumferentially averaged velocity components compare well with the measured values, while the velocity and turbulence quantities in the highly concentrated tip vortex region are under-predicted. The overall results suggest that the present approach is practicable for actual propeller design procedures.

scholarly journals A Hybrid RANS-LES Computational Fluid Dynamics Simulation of an FDA Medical device benchmark

Mechanika ◽  
2019 ◽  
Vol 25 (4) ◽  
pp. 291-298
Author(s):  
Primož Drešar ◽  
Jožef Duhovnik
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulence Models ◽  
The United States ◽  
Dynamics Simulation ◽  
Sudden Expansion ◽  
Detached Eddy Simulation ◽  
Cfd Validation ◽  
Eddy Simulation ◽  
Advection Schemes

Computational fluid dynamics (CFD) is a valuable tool that complements experimental data in the development of medical devices. The reliability of CFD still presents an issue and for that reason, no standardized approaches are currently available. The United States Food and Drug Administration (FDA) has initiated the development of a program for CFD validation, and has presented an idealized nozzle benchmark model. In this study, a nozzle flow with sudden expansion has been simulated using advanced RANS-LES turbulence models. Such models partially resolve the flow and are cheaper in computer resources and time in comparison to the Large Eddy Simulation (LES). Furthermore, they are more accurate than standard Reynolds-averaged Navier-Stokes (RANS) models. A collection of hybrid turbulence models has been investigated: Detached Eddy Simulation (DES), Stress Blended Eddy Simulation (SBES), and Scale Adaptive Simulation (SAS), and compared to a standard RANS Shear Stress Transport (SST) model. Subsequently, all models were validated by experimental results already published by different research groups. Particle Image Velociometry (PIV) experiments were performed by inter-laboratory study, and the results are available online for numerical validation.  The flow conditions in this study are only restricted to a turbulence flow at a Reynolds number of Re =6500. Complementing the turbulence models investigation, two advection schemes were tested: high resolution (HR) and bounded central difference scheme (BCD). Among all advanced models the SBES model with BCD scheme has the best agreement with the experimental values.

Applicability of Common RANS Models for the Calculation of Transient Forced to Natural Convection

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Austen D. Fradeneck ◽  
Mark L. Kimber
Keyword(s):  
Natural Convection ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Latin Hypercube Sampling ◽  
Distribution Functions ◽  
Flow Reversal ◽  
Cumulative Distribution ◽  
Quality Data ◽  
System Response ◽  
Heated Plate

Abstract The applicability of several Reynolds averaged Navier–Stokes (RANS) turbulence models in calculating the transient evolution of a buoyancy-induced flow reversal along a vertical heated plate is analyzed through the use of validation quality experimental data from the Rotatable Buoyancy Tunnel (RoBuT) facility. This benchmark attempts to capture the transient evolution from downward forced convection to upward natural convection by removing power to the blower and allowing the buoyancy force emanating from the heated plate to gradually dominate as the primary driving force. Boundary conditions and system response quantities for the numerical model are supplied from the experiment every 0.2 s during the 18.2 s transient. ASME standards are used to quantify the numerical uncertainties while the input uncertainties are handled using a Latin hypercube sampling (LHS) method based on the steady-state conditions (t=0 s). Qualitative comparisons between numerical and experimental results at several downstream locations are supported using a validation metric based on the statistical disparity between the respective empirical and cumulative distribution functions (CDFs). The results from this study show that the standard linear eddy-viscosity models have difficulty in reproducing the complex features of the flow reversal in comparison with the more intricate turbulence models such as Reynolds stress models (RSM) and low-Reynolds number variants. This study also briefly highlights the difficulties of capturing validation quality data for three-dimensional multiphysics flow, while also providing insight for the design of future experimental efforts.

Technical Note: Evaluation of Surface-Ship Resistance and Propulsion Model-Scale Database for CFD Validation

1996 ◽  
Vol 40 (02) ◽  
pp. 112-116
Author(s):  
J. Longo ◽  
F. Stern
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Technical Note ◽  
Current Status ◽  
Navier Stokes ◽  
Cfd Validation ◽  
Model Scale ◽  
Surface Ship ◽  
Future Data ◽  
Computer Codes

An evaluation is performed of the surface-ship model-scale database for computational fluid dynamics validation with regard to current status and future requirements. The specific emphasis is on data of relevance to resistance and propulsion and validation of Reynolds-averaged Navier-Stokes computer codes. The data were evaluated relative to criteria and requirements developed for geometry and flow, physics, and computational fluid dynamics validation as well as past uses. Conclusions are made with regard to the available data and past uses, and recommendations are offered for future uses of the available data and future data procurement.

Sign in / Sign up

Export Citation Format

Share Document