Hybrid spatially-evolving DNS model of flow past a sphere

VanDine, Alexandra; Chongsiripinyo, Karu; Sarkar, Sutanu

doi:10.1016/j.compfluid.2018.05.018

Cited by 17 publications

(18 citation statements)

References 22 publications

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“…The numerical methods employed to solve the governing equations are similar to DNS of our previous work (Brucker & Sarkar 2007; Pham & Sarkar 2010; VanDine, Chongsiripinyo & Sarkar 2018). The Williamson low-storage, third-order Runge–Kutta method is employed for time advancement while the discretization of spatial derivatives is achieved using a second-order, central finite difference scheme.…”

Section: Formulationmentioning

confidence: 99%

Turbulent shear layers in a uniformly stratified background: DNS at high Reynolds number

VanDine

Sarkar

2021

J. Fluid Mech.

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Section: Formulationmentioning

confidence: 99%

Turbulent shear layers in a uniformly stratified background: DNS at high Reynolds number

VanDine

Sarkar

2021

J. Fluid Mech.

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“…The consequently large time step in the BE simulation leads to considerable savings in computational time without compromising accuracy (VanDine et al. 2018).…”

Section: Hybrid Simulationmentioning

confidence: 99%

“…The grid cell in the BE simulation, which has to be sufficiently small to adequately resolve wake turbulence, is still much larger than that required to resolve the boundary layer. The consequently large time step in the BE simulation leads to considerable savings in computational time without compromising accuracy (VanDine et al 2018).…”

Section: Hybrid Simulationmentioning

confidence: 99%

“…The hybrid simulation combines two simulations: a BI one that resolves the flow around the wake generator and a body-exclusive (BE) one that resolves the far wake. The BE simulation can be a temporally evolving wake (Pasquetti 2011) or a spatially evolving wake similarly to the approach of VanDine, Chongsiripinyo & Sarkar (2018) who validated the method for a sphere wake. The use of the BI simulation avoids the drawback of regular temporal simulations, for which the choice of initial conditions introduces considerable variability in the subsequent wake evolution.…”

Section: Hybrid Simulationmentioning

confidence: 99%

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High-Reynolds-number wake of a slender body

2021

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“…Initial conditions used are generally an axisymmetric Gaussian-type profile of streamwise velocity superimposed with small-scale fluctuations, which unrealistically represents stratified wakes with F r = O(1) whose geometries are immediately asymmetric in the lee of a body. In attempts to tackle this problem, [24] conducts a temporal-flow simulation with a relevant initial condition by symmetrically extending a sub-domain from a body-inclusive simulation and [25] work around the problem by continuing the solution of a body-inclusive simulation with a spatially-evolving model.…”

Section: Introductionmentioning

confidence: 99%

Untitled

2021

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The objective of the present work is to access moderately-stratified wake statistics into the far downstream. This is accomplished via a continuation of the solution from the stratified-wake, bodyinclusive, large-eddy simulation of [1] by a temporal-model, direct numerical simulation. Simulation of stratified sphere wake at Re = U ∞ D/ν = 10 4 and F r = U ∞ /N D = 3 is performed; U ∞ , D, and N are sphere velocity, sphere diameter, and buoyancy frequency. Four findings are as follows. 1) Toward the end of the mid wake, centerline mean streamwise velocity deficit continues to decay with the power-law exponent t −0.4 ; with t = x/U ∞ is proportional to the distance (x) from the sphere. The progression of horizontal wake span is at t 1/3 but the vertical wake extent remains stagnant. 2) The beginning of transition into the late wake is found to be where the mean wake is geometrically most anisotropic. The transitioning is a gradual process that lasts 50 ≤ N t ≤ 250. 3) In the late wake, vertical profile of the defect velocity exhibits self-similarity. This self-similar state is not of Gaussian-type but better fitted with individual plane-wake self-similarity solution. The centerline defect velocity rapidly decays at a rate t −3/4 . Horizontal extension growth rate is reduced to t 1/4 , disagreeing with many previous studies. The exponential growth rate of wake height is found to be t 1/2 , an indication of the dominating viscous diffusion process. 4) Throughout the wake lifetime, deviation of density from the background state exists in the vertical center plane but small in magnitude. The deviation causes an enchancement in wake-core stratification that manifests itself until the transition into the late wake.

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Hybrid spatially-evolving DNS model of flow past a sphere

Cited by 17 publications

References 22 publications

Turbulent shear layers in a uniformly stratified background: DNS at high Reynolds number

Turbulent shear layers in a uniformly stratified background: DNS at high Reynolds number

High-Reynolds-number wake of a slender body

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