- **Fluent UDF and Scheme Programming**
(*https://www.cfd-online.com/Forums/fluent-udf/*)

- - **UDF for Herschel-Bulkely model**
(*https://www.cfd-online.com/Forums/fluent-udf/65059-udf-herschel-bulkely-model.html*)

UDF for Herschel-Bulkely modelDear All
I would to used Herschel-Bulkely model but my model don't have Yielding Viscosity. Can be any body help me to use model in Fluent for Herschel-Bulkely model only don't have the Yielding Viscosity term. Please, If any body have UDF for Herschel-Bulkely model send me.Many Thanks for help me Emad |

#include "udf.h"
#include "mem.h" DEFINE_PROPERTY(cell_viscosity, cell, thread) { real mu_lam; real K=134.0; real A=0.17; real gamma; real strain=C_STRAIN_RATE_MAG(cell, thread); if(strain==0) { gamma=11.126; } else { gamma=strain; } mu_lam=K*pow(gamma,(A-1)); return mu_lam; } |

Dear Lauren
Meny Thanks for reply. But I have some quations what mean terms K and A, I thanks the Herschel-Bulkley model have fluid yield stress where this term in your eqation. I would like to send me all terms with definetion. Emad A. My e-mail Emad_ab74@yahoo.com |

A power law index, K consistency
add the yield stress in the definition of mu_lam mu_lam=K*pow(gamma,(A-1)) + yield_stress/gamma; |

Dear
Lauren Meny Thanks for reply. I don't understand this term if(strain==0){ gamma=11.126; the number 11.126 from where equation. Many Thanks again fro help me |

i don't know exactly but it will be better to write something like
if strain < strain_min then mu_lam=mu_min if strain > strain_max then mu_lam=mu_max |

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