Large Eddy Simulation of Transitional Flow in an Idealized Stenotic Blood Vessel: Evaluation of Subgrid Scale Models

Pal, Abhro; Anupindi, Kameswararao; Delorme, Yann; Ghaisas, Niranjan S.; Shetty, Dinesh A.; Frankel, Steven

doi:10.1115/1.4027610

Cited by 19 publications

(18 citation statements)

References 29 publications

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“…Using fully structured Cartesian meshes and a very low Courant–Friedrich–Lewy (CFL) number ( C F L < 0.1), results were slightly overpredicting turbulence for the R e t h =3500 case and more largely in turbulent R e t h =5000. In the follow‐up of this work , the same group evaluated two contemporary SGS models against the classical Smagorinsky on an idealized stenotic flow model. In this work, a counter‐intuitive conclusion is drawn, endorsing the Smagorinsky model known for its many drawbacks, including too large dissipation and wrong near wall behaviour, over the advanced SGS models like the so‐called Vreman model and σ –model .…”

Section: Introductionmentioning

confidence: 99%

About the numerical robustness of biomedical benchmark cases: Interlaboratory FDA's idealized medical device

Zmijanović

Mendez

Moureau

et al. 2016

Numer Methods Biomed Eng

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The need for reliable approaches in numerical simulations stands out as a critical issue for the development and optimization of cardiovascular biomedical devices. This led the US Food and Drug Administration to undertake a programme of validation of computational fluid dynamics methods for transitional and turbulent flows. In the current investigation, large-eddy simulation is used to simulate the flow in the first benchmark medical device, and results are confronted to the existing laboratory experiments. This idealized medical device has the particularity to feature transition to turbulence after a sudden expansion. The effects of numerical parameters and low-level inlet perturbations are investigated. Results indicate a considerable impact of numerical aspects on the prediction of the location of the transition to turbulence. The study also demonstrates that injecting small perturbations at the inflow greatly improves the streamwise velocity estimation in the transition region and substantially contributes to the robustness of the flow statistical data. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 99%

About the numerical robustness of biomedical benchmark cases: Interlaboratory FDA's idealized medical device

Zmijanović

Mendez

Moureau

et al. 2016

Numer Methods Biomed Eng

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“…Underprediction of both temporal and spatial transition has been the main disadvantage of the Smagorinsky SGS model. This has been discussed by Pal et al [50] where they note that at laminar flow regions there is damping of flow instabilities, which results in a delay in transition to turbulence.…”

Section: Recirculation Zone Developmentmentioning

confidence: 85%

Influence of Shear-Thinning Blood Rheology on the Laminar-Turbulent Transition over a Backward Facing Step

Kelly

Gill

Cookson

et al. 2020

Fluids

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Cardiovascular diseases are the leading cause of death globally and there is an unmet need for effective, safer blood-contacting devices, including valves, stents and artificial hearts. In these, recirculation regions promote thrombosis, triggering mechanical failure, neurological dysfunction and infarctions. Transitional flow over a backward facing step is an idealised model of these flow conditions; the aim was to understand the impact of non-Newtonian blood rheology on modelling this flow. Flow simulations of shear-thinning and Newtonian fluids were compared for Reynolds numbers ( R e ) covering the comprehensive range of laminar, transitional and turbulent flow for the first time. Both unsteady Reynolds Averaged Navier–Stokes ( k − ω SST) and Smagorinsky Large Eddy Simulations (LES) were assessed; only LES correctly predicted trends in the recirculation zone length for all R e . Turbulent-transition was assessed by several criteria, revealing a complex picture. Instantaneous turbulent parameters, such as velocity, indicated delayed transition: R e = 1600 versus R e = 2000, for Newtonian and shear-thinning transitions, respectively. Conversely, when using a Re defined on spatially averaged viscosity, the shear-thinning model transitioned below the Newtonian. However, recirculation zone length, a mean flow parameter, did not indicate any difference in the transitional Re between the two. This work shows a shear-thinning rheology can explain the delayed transition for whole blood seen in published experimental data, but this delay is not the full story. The results show that, to accurately model transitional blood flow, and so enable the design of advanced cardiovascular devices, it is essential to incorporate the shear-thinning rheology, and to explicitly model the turbulent eddies.

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“…Temporal discretization is based on a mode splitting of barotropic and baroclinic pressure gradients (Backhaus, 1985). Vertical mixing is computed with a second-order k-ε closure scheme that is extended by two prognostic equations for the turbulent kinetic energy k and the dissipation rate ε (Umlauf and Burchard, 2005), and horizontal mixing using the scheme of Smagorinsky (1963). Further details are given in Holtermann et al (2014).…”

Section: The Circulation Modelmentioning

confidence: 99%

Lagrangian Residence Time in the Bay of Gdańsk, Baltic Sea

et al. 2019

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The impact of synoptic scale and mesoscale variability on the Lagrangian residence time (LRT) of the surface water in the Bay of Gdańsk was investigated using the results from an eddy-resolving model. The computed LRT of 53-60 days was up to four times longer than the estimated flushing time reported by Witek et al. (2003). The highest residence times were those of Puck Bay and near the coast, shallower than 50 m water depth, especially during the winter. These sites also had the highest annual mean in LRT. During the summer, when the level of biological activity is high, the LRT distribution was very heterogeneous and patchy, possibly due to the dynamics of varying eddy field and to variable wind forcing. Long-term run tracking of the inflowing water from the Vistula River (VR) showed a broad spectrum of tracer distribution. The potential impact of a much higher LRT on the near-coastal nitrogen cycle, coastal filter function and genetic differentiation is discussed, and the consequences for coastal zone management are considered. Since residence time is the most important factor regulating nutrient cycling, the incorporation of residence time into the Marine Strategy Framework Directive descriptors would result in an improved, unbiased evaluation of good environmental status.

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Large Eddy Simulation of Transitional Flow in an Idealized Stenotic Blood Vessel: Evaluation of Subgrid Scale Models

Cited by 19 publications

References 29 publications

About the numerical robustness of biomedical benchmark cases: Interlaboratory FDA's idealized medical device

About the numerical robustness of biomedical benchmark cases: Interlaboratory FDA's idealized medical device

Influence of Shear-Thinning Blood Rheology on the Laminar-Turbulent Transition over a Backward Facing Step

Lagrangian Residence Time in the Bay of Gdańsk, Baltic Sea

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