Computational Fluid Dynamics Verification Research Articles

Back pressure generated by downwash and crosswind on spatial atomization characteristics during UAV spraying: CFD analysis and verification.

During unmanned aerial vehicles (UAVs) spraying, downwash and crosswind generate back pressure in comprehensive, which changes in spatial atomization characteristics of spraying droplets. However, the process of such atomization characteristics needs to be clarified. This study focuses on the effect of rotor speed and crosswind speed on spatial atomization characteristics. The computational fluid dynamics (CFD) models of the distributions of airflow, back pressure and atomization characteristics were established, and verification was conducted by developing a validation platform. The CFD results indicated that small droplets of 65-130 μm atomized by negative pressure would be coalesced near the nozzle, while large droplets of 390-520 μm atomized by positive pressure would be aggregated further away. Crosswind caused atomization stratification with droplet sizes of approximately 90 μm, 320 μm and 390 μm. When crosswind speed increased from 3 m/s to 6 m/s, the spraying drifted from 0.5 m to 1 m. When rotor speed increased from 2000 RPM to 3000 RPM, droplet distribution was expanded and droplet particle size was more uniform. Verification results demonstrated that the spraying distribution and the droplet size variation were consistent with the CFD. Spatial atomization characteristics were highly correlated with airflow and back pressure. Moreover, as crosswind generated droplet drift and atomization stratification and downwash could improve the uniformity of droplet distribution, spraying performance was superior by enhancing downwash to restrain the adverse effect of crosswind in real applications. © 2023 Society of Chemical Industry.

A Numerical Approach to Characterize the Efficiency of Cyclone Separator

Cyclone separators are active filtering devices suitable for a variety of industrial applications from conventional cutting oil pumps to recycling liquids. Since the vortex flow inside cyclones is highly complicated, the performance and flow patterns of these filters should be thoroughly researched. Liquid–solid cyclones mostly use water. Numerical studies on cyclones using higher-viscosity oils are limited. In this study, a liquid–solid cyclone injected with medium-viscosity cutting oil containing various sized-particles was comprehensively investigated. The reliability of computational fluid dynamics (CFD) methods was verified through a comparison with the experimental results. Three models with different geometries were considered for the analysis. One model was used for CFD verification. The other two models involved adding sockets for hopper length extension and changing the shape of the bottom of the hopper. The models that changed the shape of the hopper, thus directly affecting the cyclone performance, were investigated, and each model was qualitatively compared using a validated method. In addition, particle separation efficiency was evaluated by focusing on the velocity distribution to quantitatively confirm the influence of changing the shape of the hopper. The tangential velocity was determined to be similar across all three models, while the axial velocity was different and the change in the velocity of transport of the particles affected the filter function.

High-fidelity standard model reconstruction and verification of an airliner based on point clouds.

Computational fluid dynamics (CFD) numerical simulation as the primary research tool is particularly essential for its credibility during the aerodynamic design of aircraft. To further promote CFD verification and validation on the airliner, a high-fidelity model reconstruction of the airliner is fundamental. Based on this, we put forward a novel framework, to our best knowledge, to reconstruct a high-fidelity standard model for an airliner efficiently, and the feasibility and accuracy of these reconstructed models are accessed by the CFD simulation-based validation method. First and foremost, a laser scanner was placed at each station around the airliner to scan and acquire multiview point clouds. Afterwards, the truncated least-squares-based algorithm was adopted to register these point clouds entirely. Additionally, we fitted the nonuniform rational basis spline surface based on the least-squares progressive and iterative approximation algorithm. Finally, CFD simulation results were compared and analyzed with the aerodynamic data obtained by the aircraft manufacturer under the same Mach number of the uniform model. It turns out that the coincidence between them is high, and the changing trend is basically consistent. Hence, this method is highly feasible and can establish a high-fidelity standard model of an airliner with unified high and low speeds so that its appearance, test data, and research results can be adopted as the standard data for CFD verification and validation.

Verification and validation of CFD and its application in PWR fuel assembly

Fuel assembly is one of the most important components in Pressurized Water Reactor (PWR). Mixing Vane Spacer Grid (MVG) provides support for the fuel bundle. However, the most important role for MVG is to mix the coolant and decrease the temperature gradient, ultimately enhance the heat transfer and improve Critical Heat Flux (CHF). Hence the performance of MVG are directly related to the safety and economics of PWR. Due to the complexity of MVG and the broad range of thermal hydraulic conditions involved, full scale, time consuming and costly full length rod bundle experiments (usually 5 × 5 or 4 × 4 or 6 × 6) were performed to study the complicated thermal hydraulic phenomenon. Recently, with the development of computer technology, Computational Fluid Dynamics (CFD) has become one of the most popular tools to simulate the flow field of the fuel assembly. In this paper, the method based on CFD to study the MVG performance is reviewed. The main process for CFD in simulating flow field of MVG is divided into two parts. The first part is the verification and validation of CFD codes under single phase-and two-phase flow. The second is the application of CFD for exploring the MVG performance. For the verification of single phase flow CFD simulation, mesh sensitivity, turbulent model effects were examined, the validation including axial pressure drop, lateral temperature distribution, and lateral velocity distribution. For two phase flow verification and validation, the sensitivities of different drag and non-drag forces on void fraction distribution were tested. The experimental data with a tube and an annual flow fields under two phase boiling were chosen to validate the two phase flow simulation and to cover different aspects of internal and external wall boiling effects. The verified and validated CFD codes were then used to study the performance of MVG. Considering the complexity of MVG, a separated effect study approach is presented to evaluate the performance of MVG. Another systematic approach from simple geometry to 5 × 5 MVG model to study the effect of different components, including vane, dimple, and spring were proposed for the simulation of two phase flow. Some indexes were reviewed and used to evaluate the performance of MVG.

Capillary-Driven Ejection of a Droplet from a Micropore into a Channel: A Theoretical Model and a Computational Fluid Dynamics Verification.

In this work, the problem of re-ejection of a permeating droplet through a membrane pore back to the feed channel when the transmembrane pressure (TMP) becomes zero is investigated. This problem is important in the context of oily water filtration using membranes. In particular, in the novel periodic feed pressure technique (PFPT), which has been proposed to combat membrane fouling, the TMP alternates between the operating value and zero in a periodic manner. During the period in which TMP is high, filtration occurs, and when it is zero, cleaning commences. We are particularly interested in what happens to a droplet, initially undergoing permeation, when the TMP becomes zero. It is evident that when the TMP is zero the meniscus inside the pore reverses its motion toward the feed channel rather than toward the permeate side by the action of interfacial tension force. A theoretical model is built to determine the rate at which the meniscus inside the pore advances when the TMP is zero. The conservation of momentum equation is used to establish a one-dimensional model that updates the location of the meniscus with time. The derived model considers both quasi-static and dynamic scenarios. In addition, the model accounts for both the viscosity contrast between the two fluids, as well as the gravity. A computational fluid dynamics (CFD) simulation has been built to provide a framework for model verification and validation. The model, based on quasi-static conditions, provides an overall similar trend to that obtained via CFD analysis. Nevertheless, the quasi-static model predicts a more rapid meniscus advancement inside the pore than the CFD simulation. When the dynamic contact angle is incorporated, very good matching is observed.

Finite Element Analysis and Computational Fluid Dynamics Verification of Molten Pool Characteristics During Selective Laser Melting of Ti-6Al-4V Plates.

The finite element (FE) method is used to characterize the thermal gradient, solidification rate, and molten pool sizes of Ti-6Al-4V plates in the process of selective laser melting (SLM). The results are verified by using the computational fluid dynamics (CFD) simulation. The proposed FE model contains a series of toolpath information that is directly converted from a G-code file, including hatch spacing, laser power, layer thickness, dwell time, and scanning speed generated by using Slic3r software from a CAD file. A proposed multi-layer, multi-track FE model is used to investigate the influence of the laser power, scanning speed, and scanning path on the microstructure in the Ti-6Al-4V plate built via SLM. The processing window is also determined based on the proposed FE model. The FE results indicate that, with a decrease in the laser power and an increase in the scanning speed, the morphology of the crystal grains, showing fully columnar crystals, gradually deviates from the fully equiaxed region. The formed grains are dependent on the laser power, scanning speed, and deposition position, but they are not sensitive to the scanning path, and with the deposition from the bottom layer to the top layer, the size of the formed grains is gradually increasing, which shows a good agreement with the experimental results.

RANS simulation of open propeller dynamic loads in regular head waves considering coupled oblique-flow and free-surface effect

To offer references for ventilation and load fluctuation of propeller in actual seaway, this paper presents a RANS (Reynolds-Averaged Navier-Stokes equations) investigation on open propeller dynamic loads in regular head waves at variant submergence depths, from the perspective of the coupled oblique-flow and free-surface effect. Discussions are made concerning the dynamic integral loads and single-blade loads (both axial and in-plane), and instantaneous single-blade loads at different azimuthal positions. CFD (Computational Fluid Dynamics) verification and validation are conducted based on an experiment in calm water and regular head waves conducted in a circulating water channel. As conclusions, under fully-submerged condition, single-blade load variations are related solely to the unsteady oblique-flow environment, with shifts of azimuthal positions corresponding to the maximum and minimum thrust and torque due to inflow non-uniformity. Under periodical-emerging condition, high-frequency integral-load fluctuations are identified by both simulation and experiment, resulting from the enhanced propeller-surface interactions due to upward wake inclination; this enhanced propeller-surface interaction also causes serious ventilation, abrupt rises or drops of axial single-blade loads, and destruction and dissipation of propeller vortex system. Furthermore, the self-induction effect on the load distribution non-uniformity is found to be unobvious in regular waves due to the unsteady and non-uniform inflow environment.

Parametric Design and Optimization of the Profile of Autonomous Underwater Helicopter Based on NURBS

Autonomous Underwater Helicopter (AUH) is a disk-shaped Autonomous Underwater Vehicle (AUV), and it has comparative advantage of near-bottom hovering and whole-direction turn-around ability over the traditional slender AUV. An optimization design of its irregular geometric profile is essential to improve its hydrodynamic performance. A parametric representation of its profile is proposed in this paper using Non-Uniform Rational B-spline (NURBS) curve. The parametric representation of AUH profile is described with two decision variables and several data points. Based on this parametric curve, Computational Fluid Dynamics (CFD) simulation is carried out to evaluate its hydrodynamic performance with various parameters. A predication model is established over variables’ design space using Kriging surrogate model with CFD simulation results and a Genetic Algorithm (GA) procedure is conducted to find optimal design variables, which can produce an optimum lift-drag ratio. CFD verification results confirm that AUH profile with optimized design variables can increase its lift-drag ratio by 2.11 times compared with that of non-optimized ones. It demonstrates that the parametric representation and optimization procedure of AUH profile proposed in this paper is feasible, and it has a great potential in improving AUH’s performance.

Experimental investigation of the coolant flow in the VVER reactor core with TVSA fuel assemblies

The paper presents the results of an experimental study to investigate the coolant interaction in adjoining fuel assemblies in the VVER reactor core composed of TVSA-T and upgraded TVSA FAs. The processes of the in-core coolant flow were simulated in a test wind tunnel. The experiments were conducted using models representing different portions of the VVER reactor core fuel bundle and consisted in measuring the radial and axial airflow velocities in representative areas within the FAs and in the interassembly space. The results of the experiments can be translated to the full-scale conditions of the coolant flow with the use of the fluid dynamics simulation theory. The measurements were performed using a five-channel pressure-tube probe. The coolant flow pattern in different portions of the fuel bundle is represented by distribution diagrams and distribution maps for the radial and axial velocity vector components in the representative areas of the models. An analysis for the spatial distribution of the radial and axial velocity vector components has made it possible to obtain a detailed pattern of the coolant flow about the FA spacer, mixing and combined spacer grids of different designs. The accumulated database for the coolant flow in FAs of different designs forms the basis for the engineering justification of the VVER reactor core reliability and serviceability. The investigation results for the coolant interaction in adjoining TVSA FAs of different designs have been adopted for the practical use at JSC Afrikantov OKBM to estimate the heat-engineering reliability of the VVER reactor cores and have been included in the database for verification of computational fluid dynamics (CFD) codes and detailed by-channel calculation codes.

Effect of blade pitch angle on the aerodynamic characteristics of a twisted blade horizontal axis wind turbine based on numerical simulations

The present work includes a study of the impact of varying pitch angles and angular velocity on the performance parameters of a horizontal axis wind turbine using computational fluid dynamics. Simulations have been made using commercial Ansys 15 software. Seven pitch angles are chosen for study, i.e., 0° , 5 ° , 10° , 15° , 20° , 25° , and 28°, and two angular velocity values of 1.57 rad/sec and 2.22 rad/sec are used for simulation. The turbulence model used is shear stress transport (SST) K-ω. A detailed study of the influence of pitch angle on the aerodynamic characteristics of the wind turbine is highlighted. Performance parameters like torque and power have been found to exhibit random variability with a change in wind velocity and pitch angle. The verification of computational fluid dynamics (CFD) with the standard empirical formula is highlighted. The best pitch angle is noted for the best power coefficient.

Numerical investigation of ship motions in cross waves using CFD

A computational fluid dynamics (CFD) based Unsteady Reynolds Averaged Navier–Stokes and Volume of Fluid model solver is adopted to estimate ship motion responses in bi-directional cross waves. The characteristics of cross waves are analyzed theoretically and by CFD verification at first. Then ship nonlinear motion responses and green water on deck induced by cross waves are systematically analyzed by adopting a S175 containership model sailing in different cross wave conditions such as various wave lengths, wave heading angles and forward speeds. Finally, ship safe navigational strategy is explored and corresponding operational guidance is proposed to ensure the safety of ships when encountering cross waves.

Three-phase trickle-bed reactor model for industrial hydrotreating processes: CFD and experimental verification

Catalytic hydrotreating (HDT) is a process used to remove impurities from refinery streams, reacting a given feed with hydrogen at high temperature and pressure in a trickle-bed reactor. In order to optimize the operation of such reactors, one needs information about the detailed performance of the reactor. However, mathematical models of such reactors have not received due attention in last decades. Therefore, this work aimed at revisiting a plug flow HDT model to predict the performance of industrial diesel hydrotreating reactor, which considers most of the HDT reactions, gas-liquid and liquid-solid mass transfer, as well as the influence of catalyst deactivation and quenches injection on model predictions. A fourteen pseudo-component reactional network was proposed and successfully used. Computational fluid dynamics (CFD) predictions verified the plug flow behavior of the industrial HDT reactor. Both the CFD and plug flow models were verified using real process plant data, inspecting residual sulfur content and temperature profiles, with maximum relative error of 14%. Pressure and species concentration profiles as well as the effect of inlet pressure and temperature on final sulfur content were predicted and discussed. Catalyst deactivation is an important factor for accurate prediction of industrial HDT over time of campaign.

Numerical verification for a new type of UV disinfection reactor

Abstract The traditional biological method applied to the CFD (Computational Fluid Dynamics) analyses of ultraviolet (UV) disinfection reactor associates problems such as the long experimental period and complicated process. However, the paper proposes a CFD verification for a new UV disinfection reactor. The UV dose of UV disinfection reactor in different inlet flow rates and diverse UV powers are simulated and analyzed by the ANSYS-Fluent; a separate Fortran program is made for UV dose calculations. The H2O2 solution is added to the reactor model for the · O H (hydroxyl radical)absorbance experiment and numerical results of reactor are evaluated. It is concluded that the method of detecting · O H absorbance photolysis products by imposing H2O2 solution can verify the accuracy of CFD simulation. It can be applied to the design process of UV disinfection equipment. The radiation intensity near the light source is the strongest parameter. With an increase of radial distance, the UV light intensity shows an exponential decay. The UV dose can be increased by reducing the inlet flow and increasing the lamp power. However, results indicate that the adjustment of flow rate at the entrance is superior to increasing the power of UV lamp.

CFD Verification and Validation of Wire-Wrapped Pin Assemblies

TerraPower participated in a cooperative project among industry, a national laboratory, and a university to perform verification and validation of computational fluid dynamics (CFD) methods for predicting the flow and heat transfer within fuel assemblies with hexagonally packed wire-wrapped fuel pins. This project consisted of both experimental and numerical components and used surrogate fluids and electrically heated fuel pins to substitute for liquid metal and nuclear fuel. TerraPower performed CFD simulations of the experiments using industrial-level Reynolds-averaged Navier-Stokes (RANS) turbulence modeling. These simulations of helically wire-wrapped fuel assemblies employed meshes of bare pins without the wire-wrap geometry explicitly modeled. Instead, the effect of the wire-wrap on the flow is accounted for by introducing a momentum source (MS) into the governing fluid equations. Solution validation was conducted by benchmarking the CFD simulations to the heated bundle experiments. These simulations used the as-tested boundary and operating conditions but were conducted blind. Pressure drop measurements and local temperature measurements were compared. Axial pressure drop simulation results compared well with the experiment measurements. The vast majority of the local CFD temperatures matched thermocouple measurements within the instrument uncertainty. The good agreement between simulation and experiment supports the use of RANS-based CFD simulation methods and the specific applied MS method to model wire-wrapped fuel assemblies.

The Static Instability Characteristics of Labyrinth Seals: Experiments and Computational Fluid Dynamics Verification

Abstract The paper proposed an experimental measurement to identify the fluid-induced force and static stiffness coefficients. A three-dimensional fluid model of the labyrinth seals was also established. And the static characteristics under different eccentricities and inlet pressure were studied. Theoretical results show a good agreement with the experiment results. The labyrinth seal with different eccentricity ratios produces a de-centered fluid-induced force and a negative direct static stiffness, which cause the rotor deviating from the geometric center of the stator. Both the fluid-induced force and negative direct static stiffness coefficient with a value of −13.5 kN/m to −72 kN/m increase with increasing eccentricity and inlet pressure. Particularly, the direct static stiffness coefficient shows a relatively significant increase with a high eccentricity ratio (∼>40%). The static instability is mainly due to the fact that the fluid velocity in the small clearance increases more rapidly along the leakage path. The inertial force is increased significantly and the pressure decreases. This results in a greater pressure distribution in the larger clearance. The fluid force and direct static stiffness coefficient that tend to push the rotor away from the stator center are produced, and eventually lead to the static instability of the labyrinth seal.

Investigation of the onset of the breakup of a permeating oil droplet at a membrane surface in crossflow filtration: A new model and CFD verification

In this work, a new model is introduced to determine the crossflow velocity required to dislodge permeating oil droplets at the surface of a membrane. Oil droplets at the surface of a membrane face either of four fates; namely, pinning, permeation, rejection, or breakup. The conditions at which the first three fates are realized have been, to a large extent, satisfactorily explored. The conditions for the breakup, however, do not seem to be very well defined. Although there exist few attempts to define conditions for breakup by crossflow field, they seem insufficient and lack consistency with the physics. It is, therefore, the aim of this work to provide elaborate analysis based on a clear understanding of the physics involved and the forces contributing to the breakup. A mathematical formula is developed to estimate that critical crossflow velocity at which break up occurs. This formula is derived based on the balance of torques that are generated by the interplaying forces. These forces are essentially surface tension forces and drag force. When the droplet encounters a pore opening it forms an interface and if the pressure across the opening is larger than the entry pressure, the interface advances inside the pore. When the receding interface of the droplet reaches the pore opening, the droplet pauses and anchors itself by that portion of the droplet in the pore. The droplet then continues to deform in accordance with the interplay of the imposed drag force and the generated surface force. The droplet wraps around the pore opening and the central angle of encounter increases per the imposed drag force. When the central angle of encounter reaches π radians, this represents the critical configuration beyond which the droplet breaks down to two parts. As the droplet deforms while anchored in its place, the contact line around the pore opening uncover the surface and starts to contribute towards the torque about the pivoting point. The balance of torques generated by the drag force and the interfacial force at that portion of the contact line, which makes a central angle of π radians, is used to determine that critical velocity beyond which the droplet breaks up. Several verification exercises are conducted using computational fluid dynamics (CFD) analysis to build confidence in the derived formula of the critical crossflow velocity. Based on the comparisons, the newly derived formula compares very well with the data obtained using CFD analysis.

A parametric CFD study of computer room air handling bypass in air-cooled data centers

Computer room air handling (CRAH) bypass (BP) method is an application that reduces the total fan power in air-cooled data centers by lowering CRAH fan speed. BP fans supply the complementary fraction of server airflow from warmer room air through lower-resistance floor openings into the plenum. Hence, chillers need to operate at lower temperatures less efficiently, which poses an optimization problem. The reduced-order modeling tools in the literature adequately predict fan power. However, they assume well-mixed temperature at rack inlets to deal with this optimization problem and fail to quantify the impact of ignoring temperature non-uniformities. This study includes an experimental verification of computational fluid dynamics (CFD) modeling for CRAH BP method in predicting temperatures in a data center test-cell. The subsequent parametric study uses both CFD and reduced-order modeling tools on a more representative quadrant of a large data center to investigate induced and forced CRAH BP in both enclosed and open aisle configurations as well as comparing various plenum heights, IT load and server airflow rate. Results indicate where reduced-order modeling tools perform reasonably well and where the need for CFD emerges and identify various favorable data center designs and operating conditions for CRAH BP method.

High-fidelity experimental measurements for modeling and simulation of nuclear engineering applications

Modeling and simulation performed with advanced tools are important for thorough understanding of existing power plant response to accidents; for life extension decisions of existing plants; and to support licensing activities for new power plants. The use of computational fluid dynamics (CFD) tool in nuclear R&D has gained significantly due to its capabilities to predict complex flow phenomena at very fine resolutions. High-fidelity numerical simulations including direct numerical simulation (DNS) and large-eddy simulation (LES) have been considered as reliable CFD tools for the development and validation of turbulence models along with experiments. Compared to other CFD techniques, DNS is the most computationally expensive approach, and limited to flow studies at low to moderate Reynolds numbers. LES subgrid-scale (SGS) models require the specification of model coefficients that cannot be generally used to simulate a wide spectrum of flows. Performances of LES with modified SGS model coefficients need to be verified and validated versus high-resolution experimental database or DNS results.In this paper, we present the current state-of-the-art experimental measurements in complex geometries of advanced nuclear reactors, such as turbulent flows in wirewrapped fuel bundle for liquid metal reactors and randomly packed beds for gas-cooled and molten-salt reactors. It is important to achieve an in-depth understanding of flow phenomena and complex flow characteristics within these reactor cores because they are related to the safety and design scenarios. High-fidelity experimental measurements of velocity fields are acquired featuring a combination of time-resolved particle image velocimetry (TR-PIV) and matching-index-of-refraction approaches. Experimental results are obtained at high spatial and temporal resolutions of velocity fields and the first- and second-order flow statistics are suitable for the verification and validation of CFD codes currently used in nuclear engineering applications.

Performance improvement of supersonic nozzles design using a high-temperature model

The aim of this paper is to discuss the development of new contours of axisymmetric supersonic nozzles giving a uniform and parallel flow at the exit section, to improve the aerodynamic performances compared to the minimum length nozzle, by increasing the exit Mach number and the thrust coefficient, and by reduction of the nozzle's mass, while holding the same throat section between the two nozzles. The new nozzle is named the best performance nozzle. Its form contains a cylindrical central body and an external wall for the flow redress. The study is done at high temperature, lower than the dissociation threshold of the molecules. The variation of the specific heats with the temperature is considered. The design is made by the method of characteristics. The predictor-corrector algorithm is used to make the numerical resolution of the obtained nonlinear algebraic equations. The validation of results is made by the convergence of the numerical critical sections ratio with that given by the theory. The comparison of the results is made with the minimum length nozzle since it is currently used in the aerospace propulsion. The design depends on M E, T0, y body, y*, and the mesh generation. The application is done with air. A computational fluid dynamics verification for the under nozzle expressed regime has shown that a flow separation with the wall is observed because of the side-loads, which are reduced for this new nozzle compared to the minimum length nozzle.

Steady Flow in a Patient-Averaged Inferior Vena Cava-Part II: Computational Fluid Dynamics Verification and Validation.

The embolus trapping performance of inferior vena cava (IVC) filters critically depends on how emboli flow through the IVC and, thereby, on the underlying hemodynamics. Most previous studies of IVC hemodynamics have used computational fluid dynamics (CFD), but few have validated their results by comparing with quantitative experimental measurements of the flow field and none have validated in an anatomical model of the IVC that includes the primary morphological features that influence the hemodynamics (iliac veins, infrarenal curvature, and non-circular vessel cross-section). In this study, we perform verification and validation of CFD simulations in a patient-averaged anatomical model of the IVC. Because we are most interested in the fluid dynamics that influence embolus transport and IVC filter embolus trapping, we focus our analyses on the velocity distribution and the amount of swirl and mixing in the infrarenal IVC. A rigorous mesh refinement study is first conducted at the highest flow rate condition to verify the computed solutions. To validate the CFD predictions of the flow patterns, we then compare with particle image velocimetry (PIV) data acquired in the same model in two planes (coronal and sagittal) within the infrarenal IVC at two flow rates corresponding to rest and exercise conditions. Using unstructured hexahedral meshes ranging in size from 800,000 to 102.5 million computational cells, we demonstrate that a coarse mesh may be used to resolve the gross flow patterns and velocity distribution in the IVC. A finer mesh is, however, required to obtain asymptotic mesh convergence of swirl and mixing in the IVC, as quantified by the local normalized helicity, LNH, and the volume-averaged helicity intensity, [Formula: see text]. Based on the results of the mesh refinement study, we use a moderately fine mesh containing approximately 26 million cells for comparison with experimental data. The validation study demonstrates excellent qualitative agreement between CFD predictions and PIV measurements of the velocity field at both conditions. Quantitatively, we show that the global relative comparison error, E, between CFD and PIV ranges from 3 to 11%. By performing sensitivity studies, we demonstrate that the quantitative discrepancy is attributable to a combination of uncertainty in the inlet flow rates and uncertainty associated with precisely aligning the PIV data with the CFD geometry. Overall, the study demonstrates mesh-convergent CFD simulations that predict IVC flow patterns that agree reasonably well with PIV data, even at exercise conditions where the flow in the IVC is extremely complex.