I try to simulate helical laminar flow of non-Newtonian power-law fluid through an eccentric annulus under following assumptions: isothermal, incompressible, steady state and fully developed axial flow by using finite difference method and bipolar coordinate and Fortran coding.
I simulate the fluid flow correctly based on the validation. But for high shear-thining fluid (i.e low values of power-law index npower-law
Try lowering the shearing rate. See this, http://paginas.fe.up.pt/~fpinho/pdfs/JNNFM1990.pdf
Dear Mr. Pandey
The problem is about numerical instability in the case of low power-law index, but your link is an experimental study. I got really confused!
Could you please explain what you mean?
That's because it becomes highly non-linear system. Try to progressively change power-law index may cure the problem
@ Seyed,
What parameters are you using and which formula is being implemented? I might be able to help if you give sufficient info about your codes.
Hello Mr. Shyu
Thanks for your help and comment.
I tried this, i.e I solve the equation for npower-law=0.5 and then use these value as initial guess for npower-law=0.4 or 0.3. But it didn't work.
the complete algorithm and formulas are in the attached file of the question.
Dear Mr. Pandey
The complete algorithm and formulas is available in the attached file of the question. I used stream-function formulation, SOR approach and bipolar coordinate (conformal mapping) to transform from physical domain to computational domain.
The fact that it works for >= 0.5 but not for less than 0.5 implies singular aspect of the formulation. x^n, n
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