Partial differential equation in Field Functions

adel2009 · April 24, 2013, 12:14

HELLO,
I want to Plot (Shear stress with Shear rate) in Non Newtonian fluid(Blood).
How could I write Shear rate in Field Functions?How could I write Partial differential equation in Field Functions?.Tanks
Shear rate (two Dimensional):

triple_r · May 6, 2013, 13:13

Hey,

You can use the grad() function to define velocity gradients. For example,

$\gamma_{xy}=\frac{\partial u}{\partial y}+\frac{\partial v}{\partial x}$

can be written as:

grad($$Velocity[0])[1] + grad($$Velocity[1])[0]

But I would suggest not using this method for the velocity gradients, and instead turning on the temporary storage option under the solver options (for example, under segregated fluid solver) and then using:

$$U_VelocityGrad[1] + $$V_VelocityGrad[0]

In my experience, this second method gives better results.

I hope this helps.

April 24, 2013, 12:14	Partial differential equation in Field Functions	#1
adel2009 New Member Ka. Join Date: Apr 2013 Posts: 1 Rep Power: 0	HELLO, I want to Plot (Shear stress with Shear rate) in Non Newtonian fluid(Blood). How could I write Shear rate in Field Functions?How could I write Partial differential equation in Field Functions?.Tanks Shear rate (two Dimensional):

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May 6, 2013, 13:13		#2
triple_r Member Reza Join Date: Mar 2009 Location: Appleton, WI Posts: 49 Rep Power: 6	Hey, You can use the grad() function to define velocity gradients. For example, $\gamma_{xy}=\frac{\partial u}{\partial y}+\frac{\partial v}{\partial x}$ can be written as: grad($$Velocity[0])[1] + grad($$Velocity[1])[0] But I would suggest not using this method for the velocity gradients, and instead turning on the temporary storage option under the solver options (for example, under segregated fluid solver) and then using: $$U_VelocityGrad[1] + $$V_VelocityGrad[0] In my experience, this second method gives better results. I hope this helps.