Viscosity factor in SPH non-Newtonian fluid module not working

[abu.hamad]

Hi everyone,

I am simulating a dam break with non-Newtonian Herchsel-Bulkley fluid model. I am using non-Newtonian SPH module in Ansys Rocky. It is mentioned in the manual that fluid will not freeze/stop even its shear stress comes below to yield stress value. Therefore, viscosity factor is introduced in the code so that stress comes below the yield stress then viscosity factor works and it increases the viscosity of fluid which make it thick and stop it.

I dont know why viscosity factor is not working, you can see in the attched figure that even visocisyy factor is increased upto 10,000 (even i have checked with viscosity factor = 100,000) then too it does not effect/work even one percent and i have same reults such as viscosity factor is 100. Fluid does not stop even we increase viscosity factor to 10,000 it keeps flowing very slow after 10 minutes also, i have checked this. Fluid velocity and runoff distance is same at visosity factor is 100 or 10000 for amy time such as 10 minutes or 15 minutes. Increasing in visosity factor does not bring fluid to stop/freez. I will be thankful if someone can guid me. Thanks

 

[Lucas Bertollo Baggio]

Hello,

I would suggest you reducing the Yield Stress to 2 Pa to test, for example. 

 

best,

Lucas

[abu.hamad]

Respected sir, 

I have cheked by lowering the yield stress values 1 to 3 Pa. There is zero percent effect of viscosity factor on the simulation. I have same velocity and same run off distance at given time. It seems such as viscosity factor is mssing in equation in code but its only showing in pannel. I will be thankful if you can also check by making any simulation and see whats are results. For my case, i am Using Herschel bulkley non-Newtonian fluid model and i have been used WCSPH and ISPH appraoch to check this. Thanks for you time

[Lucas Bertollo Baggio]

Hello abu,

 

we checked on the code and the viscosity factor is not missing on the equation. Unfortunately, there is a limitation here - the viscosity factor helps on decelerate the fluid, but it will never make it stop.

 

best regards,

Lucas

[abu.hamad]

Respected Sir, 

Can you please shear what model parameters did you use to check it? In my case it does not work even 1 percent as i have shoed above. I will be thankful if you can share your parameters so that i could get idea how it slowed the fluid or how did you check. Thanks

[Lucas Bertollo Baggio]

Hello,

 

Could you try using a viscosity factor of 1000, save the project without results under a different file name, and then test it again with a viscosity factor of 1 in this new file?

It should present different results.