Local Velocity Profiles Research Articles

Orifice Versus Converging-Nozzle Grid Turbulence: A Wavelet Perspective

Grids such as perforated plates are of fundamental importance in flow turbulence study and are commonly utilised to promote mixing. An orificed perforated plate (OPP) and its reversed counterpart, the converging-nozzle perforated plate (CNPP), were applied to produce quasi-isotropic turbulence inside a wind tunnel. The three orthogonal velocity components were measured using a triple hotwire at 10D downstream of the perforated plate for Reynolds numbers, ReD, 18,700 and 28,400, where D is the diameter of the perforated holes. The statistics of the grid-generated turbulence was analysed using the time-averaged local velocity profile and turbulence intensity, which revealed a more homogeneous distribution of the flow field with a higher level of turbulence for the OPP. Fourier and wavelet analyses were employed to investigate the energy of the eddies as a function of frequency and multiscale characteristics of the fluctuating velocity, respectively. At ReD = 18,700, the turbulent energy remains prominently with large-scale vortical structures which are non-intermittently present in the flow for both perforated plates. The thickness of the converging channels of the CNPP appears to provide the venue for spawning intermittent fluctuations. At higher ReD 28,400, the effect of this intermittent behaviour becomes evident for the CNPP, leading to a multiscale distribution of turbulent energy.

A generalized wall-pressure spectral model for non-equilibrium boundary layers

This study uses high-fidelity simulations (direct numerical simulation or large-eddy simulation) and experimental datasets to analyse the effect of non-equilibrium streamwise mean pressure gradients (adverse or favourable), including attached and separated flows, on the statistics of boundary-layer wall-pressure fluctuations. The datasets collected span a wide range of Reynolds numbers ( $Re_\theta$ from 300 to 23 400) and pressure gradients (Clauser parameter from $-0.5$ to 200). The datasets are used to identify an optimal set of variables to scale the wall-pressure spectrum: edge velocity, boundary layer thickness and the peak magnitude of Reynolds shear stress. Using the present datasets, existing semi-empirical models of the wall-pressure spectrum are shown unable to capture effects of strong, non-equilibrium adverse pressure gradients, due to inappropriate scaling of the wall pressure using the wall shear stress, calibration with limited types of flows and dependency on model parameters based on the friction velocity, which reduces to zero at the detachment point. To address these shortcomings, a generalized wall-pressure spectral model is developed with parameters that characterize the extent of the logarithmic layer and the strength of the wake. Derived from the local mean streamwise velocity profile, these two parameters inherently carry the effect of the Reynolds number, as well as those of the non-equilibrium pressure gradient and its history. Comparison with existing models shows that the proposed model behaves well and is more accurate in strong-pressure-gradient flows and in separated-flow regions.

Comparisons between full molecular dynamics simulation and Zhang's multiscale scheme for nanochannel flows.

In a very small surface separation, the fluid flow is actually multiscale consisting of both the molecular scale non-continuum adsorbed layer flow and the intermediate macroscopic continuum fluid flow. Classical simulation of this flow often takes over large computational source and is not affordable owing to using molecular dynamics simulation (MDS) to model the adsorbed layer flow, if the flow field size is on the engineering size scale such as of 0.01-10mm or even bigger like occurring in micro or macro hydrodynamic bearings. The present paper uses full MDS to validate Zhang's multiscale flow model, which yields the closed-form explicit flow equations respectively for the adsorbed layer flow and the intermediate continuum fluid flow. Here, full MDS was carried out for the pressure-driven flow of methane in the nano slit pore made of silicon respectively with the channel heights 5.79nm, 11.57nm, and 17.36nm. According to the number density distribution, the flow areas were respectively discriminated as the adsorbed layer zone and the intermediate fluid zone. The values of the characteristic parameters for Zhang's multiscale scheme were extracted from full MDS and input to Zhang's multiscale flow equations respectively for calculating the flow velocity profile and the volume flow rates of the adsorbed layers and the intermediate fluid. It was found that for these three channel heights, the flow velocity profiles calculated from Zhang's model approximate those calculated from full MDS, while the total flow rates through the channel calculated from Zhang's model are close to those calculated from full MDS. The accuracy of Zhang's multiscale flow model is improved with the increase of the channel height. The recent modification of the optimized potential for liquid simulation (MOPLS) model was used to calculate the interaction force between two methane molecules. In order to calculate the interaction force between the wall atoms and the methane molecules accurately, our previous non-equilibrium multiscale MDS was used. The interaction forces between the methane molecule and the wall atom were obtained from the coupled potential function by the L-B mixing rule when the fluid molecules arrived at near wall. The methane molecule diameter was obtained from the radial distribution function by using equilibrium MDS under the same initial conditions. The local viscosities across the adsorbed layer were obtained from the local velocity profile by using the Poiseuille flow method. The motion equation of the methane molecule was solved by the leapfrog method. The temperature of the simulation system was checked by Bhadauria's method, i.e., the system temperature was rectified by the velocities in the y- and z-directions. The flow velocity distributions across the channel height and the volume flow rates through the channel were also calculated from Zhang's closed-form explicit flow equations respectively for the adsorbed layer flow and the intermediate fluid flow. The results respectively obtained from full MDS and Zhang's multiscale flow equations were then compared.

Thermal and hydrodynamic analysis inside a channel partially filled with porous material

AbstractIn this work, the transfer of heat and changes in fluid pressure within a rectangular channel fairly packed with porous material have been studied numerically for various Darcy numbers and dimensionless porous layers. The model was run with the following assumptions: laminar flow, forced convection, isotropic porous material, local thermodynamic equilibrium, constant wall temperature boundary condition, and no thermal dissipation. The study covers a broad range for the dimensionless porous layer, 0 ≤ hr < 1, and the Darcy number, 10−4 < Da < 10−2. The fully developed and developing flow over the channel is investigated in numerical study. It was observed that the inertia effect may be disregarded when Da < 10−4. The local dimensionless bulk temperature distribution, pressure drop, and velocity profiles were all shown to be impacted by the Darcy number and dimensionless porous layers, according to the numerical analysis results. The maximum heat transfer rate was attained when the ratio of the porous layer inside the channel was 0.8, and the pressure gradient was the highest. Partial packing of the channel with a porous material has two advantages: it increases the rate heat transmission rate and results in a much smaller pressure drop than a filled porous medium.

Hydrodynamics in a randomly packed bed of cylindrical particles: A comparison between PR-CFD simulations and MRI experiments

Slender catalytic packed bed reactors are widely used in the chemical industry for chemical processes accompanied with significant heat liberation necessitating efficient heat removal. The employed catalyst particles are often cylindrical shaped, because these are easily manufactured via extrusion. The packing of these cylindrical particles results in a random structure of the bed causing flow maldistribution which reduces the reactor efficiency. The goal of this work is to capture the flow maldistribution with particle-resolved Computational Fluid Dynamics simulations and Magnetic Resonance Imaging experiments. By utilising the packing configuration reconstructed from the experiments, we are able to study the average fluid flow profiles and flow distribution in the bed as well as the local velocity profiles. It can be concluded that there is an overall good correspondence between the experiments and simulations. The minor deviations in the experimental and computed velocity distributions can be attributed to experimental error and slight differences in the experimental and reconstructed packing.

Numerical simulation and stability analysis of radiative magnetized hybridized ferrofluid flow with acute magnetic force over shrinking/stretching surface

The power electrical devices are being continuously trimmed down and must disperse a greater amount of heat flux, overheating has become a significant issue. Ferrofluids, also known as magnetic nanofluids, consist of solid magnetic nanoparticles that exhibit superior thermal conductivity compared to their underlying fluids, which can be either aqueous or oil based. This facilitates increased rates of convective heat transfer, but more importantly, it allows for external flow modification using a magnetic field. This work is unique in that it analyses hybridized ferrofluid flow over a shrinking/stretching surface with radiative magnetization and significant magnetic force. The governing equations were solved using the bvp4c function in MATLAB, after being transformed into ordinary differential equations (ODEs) by using similarity transformations. The system acquires a bimodal solution, and stability analysis validates the physical and dynamic stability of the first solution. The local skin friction coefficient, the local Nusselt number, the temperature and velocity profiles, and the substantial influence of governing effects are all studied and graphically displayed. The key findings are the values of Nux1Rex are decreasing for both second and first solutions as values of φCoFe2O4 are increasing. An increasing trend for the values of RexCf is observed for both second and first solutions as values of φCoFe2O4 increases. The results compareded with the results reported in literature and found a significant agreement.

Internal circulation in carrier phase slugs and its influence on the local hydrodynamics in reactive liquid–liquid segmented flow: Visualisation and PIV studies

Local velocity profiles and fluid circulation in liquid–liquid segmented flow significantly influence interphase mass transfer and associated chemical reactions in reduced dimensions. The present study considers a mass transfer-controlled pseudo first order reaction between iodine dissolved in toluene plugs (dispersed phase) and aqueous sodium hydroxide solution (carrier phase). The circulation patterns in the aqueous slugs observed during PIV experiments are correlated with the overall reaction rate. The extent of reaction is identified by decolourisation of the toluene plugs which is a result of iodine depletion. The experiments reveal that an increase in dispersed phase flow rate increases the circulation rate and local velocity within the carrier phase slugs. This is accompanied by propagation of reactant depletion zone from top to bottom within the organic plug and flattening of plug bottom. Nevertheless, the circulation remains axisymmetric with the stagnation region unchanged at r0 ∼ 0.74R.

Two-phase volume-averaged predictive theory of dilute ferrofluid spin-up flow in a rotating magnetic field

We have developed a parameter-free, two-phase, volume-averaged approach to predictively describe the spin-up flow of dilute, cluster-free ferrofluids excited by low-frequency rotating magnetic fields. Predictive validation of the model was performed through a thorough comparison with local velocity profile measurements, and it demonstrated its ability to capture the spin-up flow dynamics without the need for parameter tuning by carefully delineating the validity domain of the ferrofluid dilutedness conditions. To gain insight into the underlying flow mechanisms, we performed a systematic parametric analysis examining the effects of the induced magnetic field, the dipolar interactions between magnetic nanoparticles and the demagnetizing field. How these mechanisms shape the flow of dilute ferrofluids excited by low-frequency rotating fields in a standard spin-up flow geometry has been addressed using probabilistic nanoparticle orientational dynamics, combining Faxén's laws and the Smoluchowski equation to describe the transport of particle magnetic moments. Our findings revealed that the induced magnetic field is the primary driving force of ferrofluid spin-up flow. The dipole interactions and demagnetizing field, on the other hand, contribute only as secondary phenomena to the overall flow behaviour. Furthermore, we have discussed the potential extension of the two-phase approach, in particular with respect to the formation of chain-like aggregates under the influence of strong magnetic fields. Overall, our study provides valuable insights into the complex dynamics of ferrofluid flow and contributes to a comprehensive understanding of the key mechanisms governing the spin-up flow of dilute ferrofluids excited by low-frequency rotating magnetic fields.

Analysis of GO-MoS2/EG Powell-Eyring Fluid Transportation in Stagnation Point Flow and Heat Transfer over a Shrinking Surface

Using ethylene glycol as the base fluid, nanomaterials graphene oxide (GO) and molybdenum disulfide (MoS2) are disseminated into the fluid. The heat transfer behaviour of a non-Newtonian Powell-Eyring fluid hybrid nanofluid is evaluated together with several effects such as magnetic, suction and radiation. Ordinary differential equations (ODEs) are acquired by deriving the mathematical model in partial differential equations (PDEs) with suitable similarity transformations. The formulas are numerically estimated with the assistance of the bvp4c solver in MATLAB. The impact of parameter effects on the skin friction coefficient, local Nusselt number, entropy generation, velocity profile and temperature profile are reviewed and discussed. The aftermath revealed that skin friction and suction effects are elevated along the magnetic field. The rate of heat transmission is enhanced by improving the value of the suction parameter. Magnetic field, Eckert number and suction boosted entropy over the shrinking plate.

Surface activity characterization of synthesized polyvinyl alcohol-based nanogel at air-water interface under highly dynamic conditions

The ability to predict the behavior of nanogels at the air-water interface is critical for developing intelligent drug delivery systems. In this investigation, polyvinyl alcohol (PVA)-based nanogels were synthesized via the self-assembly crosslinking method employing fructose. The nanogels were characterized by means of FE-SEM, FTIR, and DLS analyses. The FE-SEM images confirmed the spherical morphology of the nanogels with an average diameter in the range of 18–30 nm. The polydispersity index of the nanogels, as assessed by the DLS test, was approximately 0.4. Subsequently, the impact of pure PVA and its produced nanogels on the hydrodynamics of a single air bubble ascending in aqueous solutions was explored, revealing that the presence of these molecules at the air-water interface results in a decrease in the local velocity profile (LVP) due to their surface activities. Finally, the results of the pendant drop measurements demonstrate that nanogels are more surface active than PVA.

Lagrangian Simulation Methodology for Large-Eddy Simulations of Prefilming Air-Blast Injectors

A Lagrangian framework is proposed to address liquid film and atomization modeling in large-eddy simulations (LESs) of aeronautical air-blast injectors. The Lagrangian liquid film model of O’Rourke and Amsden (“A Spray/Wall Interaction Submodel for the KIVA-3 Wall Film Model,” SAE International TP 2000-01-0271, Warrendale, PA, 2000) is improved by introducing a subgrid contact angle to better predict the film height and the resulting film dynamics. Next, the phenomenological the primary atomization model for prefilming air-blast injectors (PAMELA) proposed by Chaussonnet et al. (“A New Phenomenological Model to Predict Drop Size Distribution in Large-Eddy Simulations of Airblast Atomizers,” International Journal of Multiphase Flow, Vol. 80, April 2016, pp. 29–42) for primary atomization at the prefilmer edge is enhanced to deal with complex geometries. This model is able to predict the droplet-size probability density function from the prefilmer height and flow conditions. The original formulation relied on correlations valid for flat plates to determine the gas boundary-layer thickness, and it required a gas velocity at film height to be set by the user. These two points make its use difficult for complex configurations where there is no simple correlation for the gas boundary-layer thickness and the gas velocity at film height cannot be a priori estimated. An embedded methodology, named the automatic PAMELA, is therefore proposed in this work to automatically determine these two quantities in the simulation. For each cell of the prefilmer edge where atomization occurs, the gas boundary-layer thickness is estimated by analyzing the local velocity profile thanks to Lagrangian probes; and the gas velocity is computed from the local film height by assuming a logarithmic velocity profile. Finally, the film and primary atomization models are coupled to a secondary atomization model, and they are assessed on an industrial air-blast aeronautical injector. The average droplet velocity profiles and Sauter mean diameters are compared against experimental phase Doppler particle analyzer measurements, and they demonstrate the ability of the proposed framework to perform Lagrangian LESs of liquid injection in complex geometries.

Quasi-site-specific prediction of shear wave velocity from CPTu

A rapid and reasonable estimation of the local site shear wave velocity (Vs) profile is indispensable for site assessment. For soil deposits, researchers have developed numerous empirical correlations between Vs and piezocone penetration test (CPTu) based on a global/regional (generic) database. However, these transformations are usually biased for local sites because the generic database contains all available data without regard to site-specific differences, and the transformation uncertainty is usually non-negligible due to the complicated geology factors and measurement errors. Moreover, it is challenging to construct a site-specific correlation due to the sparse in-situ measurements. To this end, this study develops a quasi-site-specific CPTu-Vs transformation model that algorithmically combines both the generic database and site-specific measurements to provide reliable Vs prediction with uncertainty description. A generic database containing 3116 cases of 6 parameters is collected from different countries, including corrected cone tip resistance, sleeve frictional resistance, depth, soil behavior index, pore pressure ratio, and Vs. As the significant impact of soil type on CPTu-Vs correlation, independent Johnson transformation (JS) for different soil types is first adopted to normalize the generic database as a whole, ensuring the constructed model is applicable to any soil type site. Three state-of-art quasi-site-specific models are investigated for CPTu-Vs transformation: probabilistic multiple regression (PMR), the hybridization method (HYD), and the hierarchical Bayesian model (HBM). Empirical correlations and the recently-developed data-driven model (XGBoost) are also considered to illustrate the novelty of the quasi-site-specific model. The applications on three sites with different soil types show that considering soil type in JS improves model accuracy and reduces the transformation uncertainty. The HBM with multiple basic CPTu parameters performs best regarding accuracy, uncertainty, and robustness.

CFD simulation and experimental validation of multiphase flow in industrial cyclone preheaters

A hybrid multiphase model (Dense Discrete Phase Model, DDPM) coupled with a k-ω sst turbulence model, which includes gas–solid heat exchange was developed for the simulation of industrial-scale cyclone preheaters operating under high solid loadings. The model results are validated by experimental measurements from an industrial cyclone preheater with a diameter of 1.6 m, with respect to the pressure drop, gas and particle exit temperature, local gas velocity profiles, measured using the LDA, and gas temperature profiles, measured using thermocouple and FTIR. Reasonable agreement between the data from experiments and simulations was obtained. In addition, the major trends, such as changes in the pressure drop, overall heat transfer rate, and flow pattern, caused by the changes in the operating parameters can be captured accurately by the model.

Investigation of Flow Behavior of Turbulent Wall-Jet in the Viscous Shear Regime With Moving Wall Condition

AbstractThis work involves studying the effects of plate motion on the turbulent flow behavior of a wall jet stream flowing over a flat plate moving at a constant velocity in a quiescent atmosphere. A modified low-Reynolds-number turbulence model developed by Yang and Shih (YS model) is used to perform the numerical investigation. The YS model involves applying integration to a wall technique to capture the flow and heat transfer phenomenon in the near-wall region. The Reynolds number is taken as 15,000 and Prandtl number of the fluid as 7. The plate motion effect on the flow behavior is observed for the various velocity ratios Up =0−2. The velocity vector diagrams and the local velocity profiles at various axial locations are plotted to analyze the flow pattern variation with the plate velocity. Based on the investigation of velocity profiles, nearly self-similar velocity profiles are noticed for Up=0, 0.5, and 2 whereas for Up=1.0 and 1.5, the velocity profiles display similarity near the wall but diverge away from the wall. The turbulent kinetic energy (TKE) (k) and its dissipation rate (ε) within the viscous shear regime are predicted for moving plate conditions. The dissipation rate appears to be higher for higher velocity ratios. Overall, the plate motion significantly influences the flow field.

Impact of Thermal Radiation on MHD GO-Fe2O4/EG Flow and Heat Transfer over a Moving Surface

The heat transmission in a non-Newtonian hybrid nanofluid that combines particles of graphene oxide (GO) and iron dioxide (Fe2O4) with the base fluid chosen as ethylene glycol (EG) is analyzed, including the effects of radiation and magnetic influence. The hybrid nanofluid flow is assumed to be asymmetric because it flows along a horizontal shrinking surface in response to external inducements. The mathematically modelled partial differential equations (PDEs) form is then derived into ordinary differential equations (ODEs) by implementing a proper similarity transformation to the PDEs. The mathematical formulation is then algorithmically estimated employing the bvp4c solver in MATLAB. The parameters’ effects on the skin friction measurement, local Nusselt number, entropy generation, velocity profile, and temperature profile are investigated and explained. This finding illustrated that the skin friction is augmented between 13.7% and 66.5% with the magnetic field, velocity slips, and the concentration of GO particles. As for the heat transmission ratio, only thermal radiation and velocity slip effects will affect the heat upsurge with the range of 99.8–147% for taken parameter values. The entropy for the shrinking case is found to increase between 16.6% and 43.9% with the magnetic field, velocity slip, and Eckert number.

Mantle compositional structure and dynamics of the Arabia-Eurasia collision zone: Insights from integrated thermochemical modelling

The tectonic evolution of the Arabia-Eurasia collision zone is enigmatic due to our poor knowledge of the compositional structure of the Zagros keel and the sub-lithospheric mantle beneath the Iranian plateau. Here, we present a thermochemical model for the upper mantle, starting from the Arabian plate toward the Zagros keel (in SW Iran) and the Iranian plateau to the Kopet Dagh Mountains in NE Iran. The crustal and (sub) lithospheric mantle structure is constrained using receiver functions and high-resolution seismic tomography. The crustal density is obtained by converting local Vp velocity profiles to density. The presumed mantle composition/density of different tectonic units has been inferred from the composition of mantle-derived xenoliths in Pleistocene alkaline basalts of NE Iran, mantle xenoliths from Eastern Arabia, and integrated geophysical-petrological modeling of seismic tomography as well as Bouguer and geoid anomalies. Our results indicate that the lower part of the lithosphere in the Arabian plate is ∼ +25 kg/m3 denser than the sub-lithospheric mantle, which allows underthrusting of the Arabian lithosphere beneath the Iranian plateau. The Zagros core–an ultra-positive seismic velocity anomaly in the tomographic models– is modeled assuming a refractory “craton-like” composition, leading to a ∼-60 kg/m3 density contrast with its underlying fertile lithospheric mantle. We hypothesize that at least the upper ∼100 km of the hydrous Arabian lithosphere was compositionally cratonic before the collision-related shortening processes. In contrast, the anhydrous Iranian lithosphere has been refertilized during asthenosphere upwelling and mantle flows. The Iranian plateau is underlain by a cold sub-lithospheric body characterized by ∼ +25 kg/m3 density contrast with respect to the ambient asthenosphere.

Numerical simulation of jet impingement relaminarization using nonlinear eddy viscosity turbulence models

This numerical study investigated a single air jet impingement at a constant temperature. Different RANS turbulence models, namely the v2-f model and four Reynolds stress turbulence models (the linear pressure-strain model, the quadratic pressure-strain model, the stress-omega model and the stress-BSL model) were employed to simulate and compare the numerical results with other published measurement data. Here, we show that the v2-f model has better numerical precision in simulating the local Nusselt number and velocity profiles and is in good agreement with a variety of Reynold numbers. These findings can assist scientists or engineers to improve mathematical turbulence modeling and industrial equipment for further development and to enable innovation.

Stagnation-point flow and heat transfer over an exponentially shrinking/stretching sheet in porous medium with heat generation

This study seeks to examine the fluid flow at the stagnation point over an exponentially shrinking and stretching sheet in a porous medium. This study also investigates the heat transfer rate in the presence of heat generation. By using the appropriate similarity transformation, we obtained ordinary differential equations (ODEs) that are reduced from the governing system of partial differential equations (PDEs). These resulting equations are subjected to new boundary conditions and solved numerically by using BVP4C in MATLAB software. The effects of the parameters involved in this study are summarized and thoroughly discussed: the skin friction coefficient, local Nusselt number, velocity profile, and temperature profile obtained. The analysis is done by using graphical and tabular data. The observed parameters are the permeability parameter K and the heat generation parameter Q towards shrinking/stretching parameter λ. It is found that a dual solution exists for λ<0 (shrinking case), whereas the solution is unique for λ>0 (stretching case). The analysis reveals that with heat generation being increased, the skin friction coefficient is constant. However, it increases when permeability increases. The local Nusselt number decreases with heat generation being increased. However, it increases when the permeability increases.

Drag reduction and the Vogel exponent of a flexible beam in transient shear flows

Interactions between a flexible beam and a fluid in a channel are of great relevance to biological hairy surfaces, aquatic vegetation, marine life (e.g., fish gills), and many industrial systems alike. While steady state response of a beam to such flows is fairly well-explored, their behavior in the transient regime is not fully understood. A series of numerical simulations are performed to study the laminar Couette flow of an incompressible viscous fluid past an elastic beam in a two-dimensional channel. The flexible beam is perpendicular to the direction of flow, and its base is fixed to the stationary bottom of the channel. We measure the evolution of the Vogel exponent, drag reduction, and reconfiguration number during the transient and steady-state response of the fluid–structure system for different geometrical and physical properties. Our benchmark shows a good agreement between numerical and experimental observations. Our results show that the system's steady-state response at different bulk-fluid velocities can be reproduced by investigating the shear flow response during the transient regime. We define a new variable that characterizes the evolution of the local velocity profile in the proximity of the free end of the beam and use that to characterize the transient-regime response. The analysis yields insight into the competing effects of elasticity of the beam and non-linear flow response.

Simulation of the Axial-Flow Centrifugal Bubble Separator for Liquid-Fueled Molten Salt Reactors Using Eulerian Two-Fluid Model

The axial-flow centrifugal bubble separator designed for the gaseous fission product removal system in liquid-fueled molten salt reactors is simulated using the Eulerian two-fluid model coupled with the Adaptive Multiple Size Group method to account for the significant coalescence and breakup in the bubble separator. The behavior of the gas core in the bubble separator is mimicked by the symmetric interfacial area concentration model. The separator efficiency, local velocity, and pressure profiles at various conditions are compared with experimental data. Good agreement is found between the experiment and the simulation for the separator efficiency. With the coalescence and breakup being accounted for, the effect of the inlet void fraction on the separator efficiency is correctly captured. For the local pressure and velocity profiles, the agreement is only quantitative due to the simplifications on the geometry and potential limitations of the current computational fluid dynamics models. As good agreement is found for the separator efficiency, the sensitivity study is performed for various operational and design parameters with further simplified two-dimensional axisymmetric simulation.