The optimal length scale for the Smagorinsky model

Christoffers, R.B. (2017) The optimal length scale for the Smagorinsky model. Master's Thesis / Essay, Applied Mathematics.

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Abstract

The simulation of turbulence is a computationally expensive task. That is why models are used to reduce the resolution of the computation, without losing too much accuracy. One of these models is the Smagorinsky model, which simulates the interaction between the large scales and the small scales that are lost by the reduced resolution. The Smagorinsky model contains a lengthscale L, which is equal to the mesh width on an uniform computational grid. It is not clear what this value should be on a nonuniform grid. In this research different values for L are tested on different nonuniform grids. On each grid is homogeneous isotropic turbulence simulated, for which on a uniform grid a method is known for the construction of the initial field. This method is altered such that it can create an initial field for a specific set of nonuniform grids. The results of the simulations show that a large value for L results in an excess of energy at fixed wavenumbers in the spectrum. That is why the minimum function of the sizes of the gridcell is found to be the best value for L in this research.

Item Type:	Thesis (Master's Thesis / Essay)
Degree programme:	Applied Mathematics
Thesis type:	Master's Thesis / Essay
Language:	English
Date Deposited:	15 Feb 2018 08:30
Last Modified:	15 Feb 2018 08:30
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/15541

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