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JMM December 4, 2001 03:58

Non-Newtonian Fluid simulations
Hi everyone

How d'you insert properties for Non-newtonian fluid in turbulent flow. I'm a new CFX user.


Robin Steed December 4, 2001 23:25

Re: Non-Newtonian Fluid simulations

Just enter an expression for the relevant property. For example, if you want to make viscosity a function of shear rate, you would replace the value for shear stress in the fluid properties with an expression, myViscosity, where:

myViscosity = K*sstrnr^(n-1)

Where K has units of [Pa s^-1], sstrnr is the shear strain rate provided by the solver, and n is a dimensionless constant.

You may also want to put upper and lower bounds on the shear strain rate to keep the results physical during convergence.

There is a Non-Newtonian fluid tutorial which describes all this quite nicely.

Regards, Robin

JMM December 5, 2001 06:31

Re: Non-Newtonian Fluid simulations
Thanks Robin I'll take it into consideration.

Else, this is to be used for stirred vessels. I've eared Promixus does not give accurate way to draw an impeller. Is there any way to deal with non-standard impeller shape?


Robin Steed December 5, 2001 20:40

Re: Non-Newtonian Fluid simulations

I was assuming you are using CFX-5. If you are using Pro-Mixus, I'm not sure how you would do the same.

In the future, please indicate what product you are referring to in your post.

Regards, Robin

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