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Large eddy simulation of a turbulent plume in stratified medium

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Old   June 29, 2021, 14:55
Default Numerical simulation of a turbulent plume
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NITIN KUMAR
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Hi, Foamers, I am running a large eddy simulation of a turbulent plume in a density varying medium (stratified medium). I am comparing mean axial velocity with an experimental study. I found that qualitatively I m getting a good agreement. However quantitatively, There are differences that can be clearly seen in the velocity. I am trying to figure out why this difference or deviation is coming.

For details: I am using the dynamic k-equation model in OpenFOAM-5.0. I am using buoyantBoussinesqPimplefoam solver (which I modified for the stratified medium). Apart from that, the plume is a forced plume with initial buoyancy and momentum. I am using around 10 million cells for the computation.

I have also plotted turbulent kinetic energy (LES) with the experimental value on the centerline. I observed that resolved Kinetic energy is more as compared to experiment, which quite strange. I am not able to figure out what is the issue. I WILL BE very grateful if any experienced user help.

Also, I observed that the entrainment is less from the velocity contours.
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File Type: png K_comp_LES.PNG (28.6 KB, 28 views)
File Type: png w_LES_comp.PNG (28.7 KB, 30 views)

Last edited by nitinkumar@cfd; July 2, 2021 at 01:21.
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Old   September 6, 2021, 12:35
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From your second chart, it looks like the entrainment rate is higher in your LES than in the experiment, which matches the observation that the TKE levels are higher.

I know that this is an old post, but did you find a cause for the difference?
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les simulation, openfoam, plume entrainment, thermal plume, turbulence

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