Diffusion term
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where <math> \bar \nabla \phi _f </math> and <math> \Gamma _f </math> are suitable face averages. <br> | where <math> \bar \nabla \phi _f </math> and <math> \Gamma _f </math> are suitable face averages. <br> | ||
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+ | == Reference == | ||
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+ | #'''Ferziger, J.H. and Peric, M. 2002'''. "Computational Methods for Fluid Dynamics", 3rd rev. ed., Springer-Verlag, Berlin. |
Revision as of 01:08, 15 September 2005
Contents |
Discretisation of Diffusive Term
Description
Note: The approaches those are discussed here are applicable to non-orthoganal meshes as well as orthogonal meshes.
A control volume in mesh is made up of set of faces enclosing it. The figure 1.1 shows a typical situation. Where A represent the magnitude of area of the face. And n represents the normal unit vector of the face under consideration.
Figure 1.1
and are position vector of centroids of cells cell 0 and cell 1 respectively.
We wish to approaximate at the face.
Approach 1
Another approach is to use a simple expression for estimating the gradient of scalar normal to the face.
where is suitable face averages.
This approach is not very good when the non-orthogonality of the faces increases. Instead for the fairly non-orthogonal meshes, it is advisable to use the following approaches.
Approach 2
We define vector
giving us the expression:
where and are suitable face averages.
Reference
- Ferziger, J.H. and Peric, M. 2002. "Computational Methods for Fluid Dynamics", 3rd rev. ed., Springer-Verlag, Berlin.