PIV Experimental Data Research Articles

Experimental and numerical study of mixed convection heat transfer in a vented cavity partially filled with a porous medium: Effects of reynolds and rayleigh numbers on Nusselt number and flow regimes

This article presents a comprehensive investigation of mixed convection flow and heat transfer within a vented, partially side-heated cubical cavity, incorporating a porous medium with low-conductivity square-shaped inclusions. The study encompasses an extensive range of Rayleigh numbers (106 < Ra < 6 × 106) and Reynolds numbers (200 < Re < 4000) while maintaining a fixed Prandtl number of Pr = 0.71. This investigation spans over three decades in Richardson numbers (Ri = Ra/(Re2 Pr)), aiming to discern the interplay between the Nusselt number, Nu, and the Richardson number. Our understanding of Nusselt number dependencies is enhanced by combining PIV measurements of heat transfer and velocity fields with temperature field data. The study uses both experimental and numerical PIV data, incorporating porous media representation to reveal heat transfer scaling with both Reynolds and Rayleigh numbers. Computational Fluid Dynamics (CFD) methods are used to explore the complex physical behavior under different flow conditions. Three distinct flow and heat transfer regimes have been identified, predicated upon the Richardson number. For Ri < 25, the flow structure and Nusselt number exhibit similarities with pure forced convection, where the Nusselt number scales as Nu ∼ Re0.6, independent of the Rayleigh number. Conversely, for Ri > 70, natural convection dominates the vicinity of the heating wall, rendering the Nusselt number less sensitive to Reynolds number variations and predominantly dictated by the Rayleigh number. Notably, the intermediate regime, ranging from 25 < Ri < 70, witnesses a competition between upward-directed natural convection flow at the heating wall and downward-directed forced flow, culminating in a minimum effective Nusselt number.

Analysis of the turbulent flow in a partially blocked wire-wrapped rod bundle using LES with wall functions

One of the most promising nuclear reactor designs is the Liquid-Metal Fast Reactor (LMFR). Its fuel assembly consists of rods containing the fuel material, arranged in a triangular lattice and covered by a hexagonal duct. The rods are separated with wire spacers that are helically wrapped around each fuel pin. Because this geometry is tight and compact, accumulation of debris, cladding deformation or detachment of the wires may generate a partial or total flow blockage of coolant subchannels at different locations. The understanding of the coolant behavior in LMFR fuels under the influence of a partially blocked flow area is required for a thorough safety assessment. A Large Eddy Simulation (LES) with wall functions was executed to simulate the flow on a 61-pin wire-wrapped rod bundle under the presence of a blockage located on the bundle periphery to simulate an abnormal operation condition. The Reynolds number was Re=17000, which is in the turbulent regime. Results of mean velocity and root mean square (rms) fluctuating velocity profiles were compared with PIV experimental data from the Texas A&M Thermal-Hydraulic Research Lab. Both mean and rms velocities were found in reasonable agreement with the experimental data among different locations because the simulation results were within 2σ from the PIV measurements. A pressure form loss coefficient due to the blockage was calculated and found to be Kloss=1.0455. The fluctuating velocities revealed a pair of shear layers that formed on each side of the blockage carrying the highest turbulent intensities. A spectral analysis was conducted to visualize the dominant frequencies on the turbulent flow in the recirculation region. The spatial–temporal two-point cross-correlations based on the fluctuating velocities were calculated at different points along the shear layer and were used to estimate integral lengths scales and convection velocities. The cross-correlations showed larger structures at higher axial elevations from the blockage rear wall. The length scales were found in the range of 3 to 21 mm while the magnitudes of the convection velocities presented values between 0.69U¯in to 1.39U¯in, where U¯in is the inlet velocity. Proper orthogonal decomposition (POD) analysis was utilized to extract the dominant modes in the fluctuating flow. Large flow structures and low frequency time signals were observed for the lowest order modes.

PIV Measurement and Simulation of Building Thermal Plume under No-wind Conditions

To investigate the buoyancy characteristics of building façades, this study deals with experimental and numerical investigations on building façade flow and temperature field in different façade temperature conditions with different height-aspect ratio of building facade. PIV measurements are conducted in a static wind platform for obtaining the mean velocity, the vertical velocity and the horizontal velocity around the building surface. To simulate the plume characteristics accurately, this study adopt three numerical model and compared the numerical results with the PIV experimental data. The result indicated that the simulation result of the RNG k-ε model best agreement with experimental data. Analysis of numerical results indicated that the wind speed kept increasing in the vertical direction, while the wind speed first increased and then decreased in the horizontal direction. The air temperature tended to be constant in the vertical direction, but air temperature first drooped sharply and tended to be constant in the horizontal direction. As the heat flow density increases, the building facade plume strength increases. When the wall heat flow increases from 100W/m2 to 200 W/m2, the maximum velocity of the wall increases by 1.6 m/s and the temperature increases by 15 °C.

Three-dimensional flow field reconstruction in the wake of a confined square cylinder using planar PIV data

A method is presented to perform the three-dimensional reconstruction of the velocity field in laminar flows using planar PIV data. The developed method relies on a convenient, repeated application of two data processing tools developed by two of the authors and called the higher order dynamic mode decomposition and the spatio-temporal Koopman decomposition. The present reconstruction method is an extension of a general method recently presented by three of the authors (Pérez et al., 2020), in which synthetic PIV data (obtained via numerical simulation) along three mutually orthogonal families of planes were used. In this article, instead, actual experimental data are considered, which requires additional data processing tools, developed in the article, to both cope with experimental noise and synchronize the various PIV datasets obtained in different timespans. The method is applied to analyze the wake of a square cylinder confined in a channel, at moderate Reynolds number. Due to limitations of the experimental setup used to obtain data for this configuration, only two families of planar PIV measurements are available that are contained in planes parallel to the sides of the channel. Because of this limitation, only the streamwise velocity component is three-dimensionally reconstructed. The performance of the method is tested in the wake of the confined square cylinder, comparing the reconstructed data with experimental PIV data measured on additional test planes (not used in the reconstruction). The obtained reconstructions of the streamwise velocity are reasonably accurate.

Influence of Turbulence in Aorta-like Tube: Computational and Experimental Study

The presented paper aims at comparison of modelling approaches to a pulsatile fluid flow in aorta-like tube; it investigates their influence on the shape of the velocity profiles and waveforms, and consequently on wall shear stress. Comparisons of computational results between rigid and compliant tubes with laminar and low Re turbulent models of fluid are presented. The results were validated with PIV experimental data through the velocity profile in the half-length section of the tube for both cases (rigid and compliant) and the overall agreement was very good, almost perfect for the rigid case. Frequency of the pulse pump in the experimental circuit was 1Hz, the diameter of the tube ~ 20 mm, and maximum deformation of the compliant tube during a period was 12%. The turbulent model improved the agreement with the experimental data by flattening the velocity profiles in both cases, but the effect was much more pronounced for the compliant tube, especially during the deceleration phase. This work confirms the hypothesis stated by Brindise and Vlachos (2018) that a longer deceleration phase triggers transition to turbulence. We put foundations for extension of this hypothesis to compliant tubes where this conclusion was confirmed for physiological Reynolds and Womersley numbers. The main outputs of this study are: (i) the length of deceleration phase should be considered (in addition to the geometry or severity of stenosis) in decision whether fluid simulations should be performed with or without laminar flow assumption; (ii) for fluid simulations of blood vessels considering their compliance, a special care should be devoted to time synchronization between BCs to prevent unphysiological waveforms.

Performance of turbulence models for flow prediction in a mould of continuous steel caster

The flow of molten steel in a mould during continuous casting process is nowadays most often studied using numerical approach. With such an approach, appropriate numerical tools have to be selected to achieve physically sound results. Within this work we focus on performance of different turbulence models for the case of casting of steel billets with single SEN port oriented in vertical, downward direction. Only fluid dynamics aspect of the casting process is considered, while all other phenomena are disregarded at this stage. Simulations were performed with commercial CFD package ANSYS Fluent with k-ε, k-ω and SAS turbulent models. The geometric model, material properties and process conditions are closely matched to those from our experimental water model studies, which is typically not done. Hence, the difference between the experiments and the numerical simulation originates only due to turbulence model performance. The experimental PIV data from the water model experimental system is used to benchmark the performance of various turbulence models. The models are compared based on lateral dispersion of the liquid jet exiting submerged entry nozzle (SEN) and formation of recirculation zones around the SEN. The results show that while all three models are capable of capturing general flow features, only the SAS model predicts finer turbulent structures and reasonably captures the flow behaviour in temporal domain.

Experimental Interpretation of Compression Ignition In-Cylinder Flow Structures

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Understanding and predicting in-cylinder flow structures that occur within compression-ignition engines is vital if further optimisation of combustion systems is to be achieved. To enable this prediction, fully validated computational models of the complex turbulent flow-fields generated during the intake and compression process are needed. However, generating, analysing and interpreting experimental data to achieve this validation remains a complex challenge due to the variability that occurs from cycle to cycle. The flow-velocity data gathered in this study, obtained from a single-cylinder CI engine with optical access using high-speed PIV, demonstrates that significantly different structures are generated over different cycles, resulting in the mean flow failing to adequately reflect the typical flow produced in-cylinder. Additionally, this high level of variability is shown by the work to impact the assessment of turbulence throughout the cycle, influencing the values often used to validate mathematical models. The original work in this paper analyses experimental PIV data from the single cylinder engine, to characterise the differences between individual cycles’ bulk flow structures and the resultant turbulent fields. The analysis approach presented uses proper orthogonal decomposition (POD) and spatial filtering to interpret the progression of the flow structures and energy throughout compression, giving an understanding of the actual flow structures that are most likely to be produced in the engine. This analysis of the data provides a meaningful understanding of the nature of the bulk flow variations and how the turbulent field develops over a given cycle, from the intake stroke to the end of compression.&lt;/div&gt;&lt;/div&gt;

Computational modeling of the Food and Drug Administration's benchmark centrifugal blood pump.

In order to simulate hemodynamics within centrifugal blood pumps and to predict pump hemolysis, CFD simulations must be thoroughly validated against experimental data. They must also account for and accurately model the specific working fluid in the pump, whether that is a blood-analog solution to match an experimental PIV study or animal blood in a hemolysis experiment. Therefore, the Food and Drug Administration (FDA) benchmark centrifugal blood pump and its database of experimental PIV and hemolysis data were used to thoroughly validate CFD simulations of the same blood pump. A Newtonian blood model was first used to compare to the PIV data with a blood analog fluid while hemolysis data were compared using a power-law hemolysis model fit to porcine blood data. A viscoelastic blood model was then incorporated into the CFD solver to investigate the importance of modeling blood's viscoelasticity in centrifugal pumps. The established computational framework, including a dynamic rotating mesh, animal blood-specific fluid properties and hemolysis modeling, and a k-ω SST turbulence model, was shown to more accurately predict pump pressure heads, velocity fields, and hemolysis compared to previously published CFD studies of the FDA centrifugal pump. The CFD simulations were able to match the FDA pressure and hemolysis data for multiple pump operating conditions, with the CFD results being within the standard deviations of the experimental results. While CFD radial velocity profiles between the impeller blades also compared well to the PIV velocity results, more work is still needed to address the large variability among both experimental and computational predictions of velocity in the diffuser outlet jet. Small differences were observed between the Newtonian and viscoelastic blood models in pressure head and hemolysis at the higher flow rate cases (FDA Conditions 4 and 5) but were more significant at lower flow rate and pump impeller speeds (FDA Condition 1). These results suggest that the importance of accounting for blood's viscoelasticity may be dependent on the specific blood pump operating conditions. This detailed computational framework with improved modeling techniques and an extensive validation procedure will be used in future CFD studies of centrifugal blood pumps to aid in device design and predictions of their biological responses.

Probabilistic evaluation of streamline topologies for the detection of preferential flow configurations in PIV applications

While PIV allows the extraction of instantaneous streamlines, the availability of typically thousands of patterns hampers a statistical understanding of the underlying flow topology. A particular application is oscillating gas jets, encountered in scientific and industrial studies dealing with mass transfer and flow control. Multiple methods, such as statistical moments (including mean, variance, skewness, and kurtosis), proper orthogonal decomposition (POD), and Hartigan’s dip test are common post-processing methodologies. However, as demonstrated in this paper, they do not provide sufficient in-depth information from a statistical perspective to attribute probabilities to potential flow topologies. In this work, a novel approach to describe probability distributions based on extracted streamline patterns is proposed. Based on the available streamline patterns, the convolution with adaptive Gaussian kernels reveals the probability density function of the flow topology. The proposed methodology, as well as more traditional post-processing approaches, are assessed on the basis of synthetic flow fields and experimental PIV data of oscillating impinging gas jets, demonstrating the added value of the streamline probability map in characterising the scrutinised flow.

Fast 3D flow reconstructions from 2D cross-plane observations

A computationally efficient flow reconstruction technique is proposed, exploiting homogeneity in a given direction, to recreate three-dimensional instantaneous turbulent velocity fields from snapshots of two dimension planar fields. This methodology, termed as ’snapshot optimisation’ or SO, can help to provide 3D data sets for studies which are currently restricted by the limitations of experimental measurement techniques. The SO method aims at optimising the error between an inlet plane with a homogeneous direction and snapshots, obtained over a sufficient period of time, on the observation plane. The observations are carried out on a plane perpendicular to the inlet plane with a shared edge normal to the homogeneity direction. The method is applicable to all flows which display a direction of homogeneity such as cylinder wake flows, channel flow, mixing layer, and jet (axisymmetric). The ability of the method is assessed with two synthetic data sets, and three experimental PIV data sets. A good reconstruction of the large-scale structures is observed for all cases. The small-scale reconstruction ability is partially limited especially for higher dimensional observation systems. POD-based SO method and averaging SO variations of the method are shown to reduce discontinuities created due to temporal mismatch in the homogenous direction providing a smooth velocity reconstruction. The volumetric reconstruction is seen to capture large-scale structures for synthetic and experimental case studies. The algorithm run time is found to be in the order of a minute providing results comparable with the reference. Such a reconstruction methodology can provide important information for data assimilation in the form of initial condition, background condition, and 3D observations.

Three-dimensional simulation of ionic wind in a laminar premixed Bunsen flame subjected to a transverse DC electric field

The role of the ionic wind effects on modifying flame dynamics was demonstrated by detailed computational models. Full three-dimensional simulations were conducted to reproduce and describe the response of a laminar premixed methane–air Bunsen flame subjected to a transverse DC electric field at saturation condition. The chemical kinetic mechanism employed a methane–air skeletal mechanism with an optimized ionization model to predict the positive and negative ions that are important for generating the electric currents. Given the strong dependence of the ionic wind on the amount of charged species created by chemi-ionization, the ion production rate was optimized to match the measured saturation current. The simulation successfully reproduced the flame tilt toward the cathode. The ionic winds blowing from the flame toward the electrodes in both rightward and leftward directions were also captured. The calculated flow field is qualitatively consistent with the PIV experimental data. Accurate description of the three-body electron attachment to oxygen and the charge transfer reactions generating heavy anions was found to be critical in simulating the flame–electric field interaction. This is a first demonstration of the ionic wind effect by full three-dimensional simulations. Further investigation by both experiment and modeling are required in future work to address quantitative differences.

Characterize Collective Lysosome Heterogeneous Dynamics in Live Cell with a Space- and Time-Resolved Method.

While studies of collective cell migration and bacteria swarming have tremendously promoted our fundamental knowledge of the complex systematic phenomena, the quantitative characterization of the collective organelles movement at subcellular level is yet to be fully explored. Here we tagged the lysosomes in live cells with fluorescent probe and imaged their spatial motion with wide field microscopy. To quantitatively characterize the collective lysosomal behavior with high spatiotemporal heterogeneity dynamics, we developed the particle collective analysis (PECAN) method based on the single particle tracking techniques. Thousands of trajectories were detected and analyzed in each single cell. The reliability was validated by comparing with traditional PIV method, simulated and experimental data sets. We show that the lysosomes in live cells move collectively with spatial heterogeneous and temporal long-term correlated dynamics. Furthermore, the continuous wavelet analysis suggested the existence of collective lysosomal oscillation in mouse neural cells. Generally, our method provides a practical workflow for characterizing the collective lysosomal motions which can benefit related areas such as organelles mediated drug delivery and cell activity profiling.

An Eulerian- Lagrangian numerical method to predict bubbly flows

A large-eddy simulation based Eulerian-Lagrangian model is employed to study bubble plumes in an open channel with crossflow. The numerical results are validated with PIV experimental data. Good agreement between simulated and observed velocities is found. The impact of the crossflow on the structure of the plume and the resulting turbulent structures are described.

On the emerging flow from a dual-axial counter-rotating swirler; LES simulation and spectral transition

The LES of a dual counter-rotating axial swirler in a confined rectangular configuration was performed under cold flow conditions. As the first objective of this paper, the grids were constructed based on a primary RANS simulation and then refined relative the Kolmogorov length scale using a field function. This greatly aided the construction of a very fine and effective grid whereby all the required criteria for an LES could be met. For the sake of validation, results in terms of mean structures were compared to existing 2D PIV experimental data using water as the working fluid. The achievement of very good agreement between the results has presented the opportunity to study the flow behavior in unsteady state conditions. The available experimental facility suffers from a similar drawback and always results in measurements a few millimeters after the flare down to downstream, while the region before the flare with high swirling interaction remains inaccessible. The second objective of this study was to study the flow behavior merely within the region before the flare location. Previous investigations have shown that the inner axial swirler greatly reduces the interaction with the outer counter-rotating swirler; a few millimeters away from the swirler, there is no sign of the inner swirler motion. Additionally, previous studies have related the formation of Precessing Vortex Core (PVC) within the central core to the peaks of the pressure or axial velocity spectrum. In addition, in some cases, up to two distinct peaks have been reported at the swirler mouth [1–3]. However, the spectrum analysis under iso-thermal conditions at the region inside the swirler, where the inner swirler dominates the flow, showed a higher potential for instabilities, with three to four distinct peaks. It was observed that, moving forward, the number of peaks is decreased, and in certain areas where the experimental measurement is applicable, the number of peaks decreased to two and one distinct points. In addition, the co-variance of the identified regions of axial and tangential velocity showed a higher correlation. The data show that the central axis corresponds to a lack of peaks of instabilities, whereas further away in the radial direction, several peaks exist. These results both emphasize the importance of the region inside the swirler where the primitive mixture of fuel and swirling air is constructed and aid in identifying the source of instabilities.

A numerical study of intake valve jet flapping in a gasoline direct injection engine

This paper presents findings from a numerical study of intake valve jet flapping within a gasoline direct injection (GDI) engine, using a large eddy simulation (LES) turbulence modelling approach. The experimental test case and computational setup, including choice of sub-grid scale (SGS) turbulence model, are presented and discussed. An example cycle where intake valve jet flapping is seen to be prominent is discussed in detail. Intake valve jet flapping was found to be initiated as a consequence of turbulent fluctuations in the intake valve curtains. Cycle-by-cycle variations in valve curtain mass flux and the subsequent jet flapping events are investigated and significant cyclic variability is found. It was observed that when an ensemble-averaging procedure, typically used in LES simulations and experimental PIV data post-processing, is applied, due to the cyclic variability of the variations in valve curtain mass flux, most of the information related to this flow phenomenon is lost.

Secondary flow visualization on stagnation row of a combined impingement and film cooled high-pressure gas turbine nozzle guide vane using PIV technique

In this study, the local jet velocity distribution for a combined impingement and film cooled high-pressure nozzle guide vane system was analyzed, using flow visualization and PIV-assisted measurement. The measurements including flow visualization were performed on the stagnation row of an NGV to understand its complex flow pattern. PIV technique was used to measure the effused coolant jet exit velocity field in two-dimensional vertical planes. The computations were performed by ANSYS FLUENT 14.5 SOLVER using shear stress transport (SST) k-ω turbulence model. Three laboratory test cases that correspond to inlet coolant mass flow rates of 0.0032, 0.0045 and 0.0054 kg/s, at the region of an FIT, were studied. The numerical results for the spanwise coolant velocity at stagnation row of the film holes agreed well with the PIV experimental data on the same vane configuration.

Investigation of rotating stall for a centrifugal pump impeller using various SGS models

The accurate modeling and prediction of the rotating stall in a centrifugal pump is a significant challenge. One of the modeling techniques that can improve the accuracy of the flow predictions is the large eddy simulation (LES). The quality of the LES predictions depends on the sub-grid-scale (SGS) model implemented in the LES. This paper assesses the influence of various SGS models that are suitable for predicting rotating stall in a low-specific speed centrifugal pump impeller. The SGS models considered in the present work include the Smagorinsky model (SM), the dynamic Smagorinsky model (DSM), the dynamic non-linear model (DNM), the dynamic mixed model (DMM) and the dynamic mixed non-linear model (DMNM). The results obtained from these models are compared with the PIV and LDV experimental data. The analysis of the results shows that the SGS models have significant influences on the flow field. Among the models, the DSM, the DMM and the DMNM can successfully predict the “two-channel” stall phenomenon, but not the SM and the DNM. According to the simulations, the DMNM gives the best prediction on the mean velocity flow field and also indicates improvements for the simulation of the turbulent flow. Moreover, the high turbulent kinetic energy predicted by the DMNM is in the best agreement with the experiment data.

Experimental Investigation of Secondary Flow Structures Downstream of a Model Type IV Stent Failure in a 180° Curved Artery Test Section.

The arterial network in the human vasculature comprises of ubiquitously present blood vessels with complex geometries (branches, curvatures and tortuosity). Secondary flow structures are vortical flow patterns that occur in curved arteries due to the combined action of centrifugal forces, adverse pressure gradients and inflow characteristics. Such flow morphologies are greatly affected by pulsatility and multiple harmonics of physiological inflow conditions and vary greatly in size-strength-shape characteristics compared to non-physiological (steady and oscillatory) flows (1 - 7). Secondary flow structures may ultimately influence the wall shear stress and exposure time of blood-borne particles toward progression of atherosclerosis, restenosis, sensitization of platelets and thrombosis (4 - 6, 8 - 13). Therefore, the ability to detect and characterize these structures under laboratory-controlled conditions is precursor to further clinical investigations. A common surgical treatment to atherosclerosis is stent implantation, to open up stenosed arteries for unobstructed blood flow. But the concomitant flow perturbations due to stent installations result in multi-scale secondary flow morphologies (4 - 6). Progressively higher order complexities such as asymmetry and loss in coherence can be induced by ensuing stent failures vis-à-vis those under unperturbed flows (5). These stent failures have been classified as "Types I-to-IV" based on failure considerations and clinical severity (14). This study presents a protocol for the experimental investigation of the complex secondary flow structures due to complete transverse stent fracture and linear displacement of fractured parts ("Type IV") in a curved artery model. The experimental method involves the implementation of particle image velocimetry (2C-2D PIV) techniques with an archetypal carotid artery inflow waveform, a refractive index matched blood-analog working fluid for phase-averaged measurements (15 - 18). Quantitative identification of secondary flow structures was achieved using concepts of flow physics, critical point theory and a novel wavelet transform algorithm applied to experimental PIV data (5, 6, 19 - 26).

Statistical analysis of turbulent super‐streamwise vortices based on observations of streaky structures near the free surface in the smooth open channel flow

AbstractLong streamwise‐elongated high‐ and low‐speed streaks are repeatedly observed near the free surface in open channel flows in natural rivers and lab experiments. Super‐streamwise vortex model has been proposed to explain this widespread phenomenon for quite some time. However, statistical evidence of the existence of the super‐streamwise vortices as one type of coherent structures is still insufficient. Correlation and proper orthogonal decomposition (POD) analysis based on PIV experimental data in the streamwise‐spanwise plane near the free surface in a smooth open channel flow are employed to investigate this topic. Correlation analysis revealed that the streaky structures appear frequently near the free surface and their occurrence probability at any spanwise position is equal. The spanwise velocity fluctuation usually flows from low‐speed streaks toward high‐speed streaks. The average spanwise width and spacing between neighboring low (or high) speed streaks are approximately h and 2h respectively. POD analysis reveals that there are streaks with different spanwise width in the instantaneous flow fields. Typical streamwise rotational movement can be sketched out directly based on the results from statistical analyses. Point‐by‐point analysis indicates that this pattern is consistent everywhere in the measurement window and is without any inhomogeneity in the spanwise direction, which reveals the essential difference between coherent structures and secondary flow cells. The pattern found by statistical analysis is consistent with the notion that the super‐streamwise vortices exist universally as one type of coherent structure in open channel flows.

Numerical modelling and validation of the air flow maldistribution in the cooling duct of a horizontal display cabinet

Air maldistribution strongly affects the performance of Open Refrigerated Display Cabinets (ORDC). Computational Fluid Dynamics (CFD) can be a useful approach to model both causes and effects of air-side maldistributions. One of the main drawbacks is the complexity of the resulting model and the high computational costs. In this paper, a numerical model of the air channel of an ORDC is presented and validated. The numerical set up was oriented to reduce the computational load, while maintaining a good agreement with experimental PIV data. Results highlighted the great importance of the correct set up of the inlet boundary and of the evaporator volume description. In addition, the modelling of the flow transition from turbulent to laminar inside the evaporator volume was proven to be critical to obtain a correct wake description downstream the evaporator.