General CFD FAQ
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== Physics == | == Physics == | ||
=== What is the difference between the Reynolds decomposition and LES filtering? === | === What is the difference between the Reynolds decomposition and LES filtering? === | ||
| - | The Reynolds decomposition separates the velocity field into an average component and a fluctuating component. '''The time average of the fluctuating component is identically zero'''. In LES, a filtering operation is performed to decompose the velocity field into a ''filtered'' velocity field and a ''filtered residual'' field. The | + | The Reynolds decomposition separates the velocity field into an average component and a fluctuating component. '''The time average of the fluctuating component is identically zero'''. In LES, a filtering operation is performed to decompose the velocity field into a ''filtered'' velocity field and a ''filtered residual'' field. The crucial difference between both methods is |
| + | *The filtered velocity field is a '''random variable''' while the average field (Reynolds) is not | ||
| + | *The time average of the residual field is generally '''nonzero''' while it is identically zero for fluctuating component in the Reynolds decomposition. | ||
== Numerics == | == Numerics == | ||
=== What is the difference between FEM, FVM and FDM? === | === What is the difference between FEM, FVM and FDM? === | ||
Revision as of 08:12, 5 December 2005
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Contents |
Physics
What is the difference between the Reynolds decomposition and LES filtering?
The Reynolds decomposition separates the velocity field into an average component and a fluctuating component. The time average of the fluctuating component is identically zero. In LES, a filtering operation is performed to decompose the velocity field into a filtered velocity field and a filtered residual field. The crucial difference between both methods is
- The filtered velocity field is a random variable while the average field (Reynolds) is not
- The time average of the residual field is generally nonzero while it is identically zero for fluctuating component in the Reynolds decomposition.
Numerics
What is the difference between FEM, FVM and FDM?
Describe differences between the finite volume method, the finite element method and the finite difference method...
