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Old   January 11, 2008, 05:24
Default multiplicity of solutions
  #1
student
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Dear Sir,

I am new to Cfd . I have seen a cavity problems produces multiple of solutions. What does it mean ? can any one explain this ? many thanks .
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Old   January 11, 2008, 08:30
Default Re: multiplicity of solutions
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Giovanni
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Hi, as You know N-S equations are non-linear PDE, insofar these lead to significant mathematical problems about existence and uniqueness of the solution, in particulary up today no one was able to proof any kind of general theorem about uniqueness of N-S equations'solution. So different discretization scheme ad turbolence modelling choice can lead to different solution, CFD analisys is affected by this, and You can trust your CFD results only after an accurate validation process, involving check of convergence, the physical sense, (i.e. if your fluid flows from low pressure to high pressure zone you have some problem...) and possibly the agreement with available experimental data and empirical correlations.

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Old   January 11, 2008, 09:48
Default Re: multiplicity of solutions
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A.K.
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Sometimes, the multiplicity of numerical solutions is caused by a bifurcation of exact solutions to the N-S equations, irrespectively of the discretization. In such cases, multiple numerical solutions simulate real flows which occur in actual practice.
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