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Macro to set Wall Shear Stress

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Old   November 15, 2003, 18:00
Default Macro to set Wall Shear Stress
  #1
Satish
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hi

can anyone help me in writing a udf to set the wall shear stress as below

Wall Shear Stress = (5/16)*(density*sqrt(2*pi*R*T))*((3/4)*(viscosity/density*temp)*dt/dxw)

Heat Flux = sqrt(2*pi*R*T)*C*(5*density*Cp/16)*(Tw - Tg)

here i need to write this in DEFINE_ADJUST as i need to update the value for every iteration. I know the macros for all the terms in the above eqn. except the wall shear stress and heat flux. Can any one help me in this

dt/dxw = derivative of temperature wrt x at the wall

Thanks

Satish
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Old   November 16, 2003, 17:34
Default Re: Macro to set Wall Shear Stress
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Ajay Rao
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But with DEFINE_ADJUST how would you get the thread of of wall ? So that you could loop over it. If you find something let me know , i need it in my calculations ! Thanks , Ajay
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Old   November 16, 2003, 17:47
Default Re: Macro to set Wall Shear Stress
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Satish
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I think U can use Lookup_Thread and get the thread.

Do u know the macro for Wall Shear Stress ?

Thanks Satish
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Old   November 16, 2003, 19:33
Default Re: Macro to set Wall Shear Stress
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Ajay Rao
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Oh yeah Right , I forgot about the Lookup_Thread ! I tried calculating the derivatives for shear stress on the wall by finding the derivatives at the cell centroid C_DUDX rather than the face. My drag force is completly wrong ! Still working on it . WIll post it if i come up with something.

Thanks, Ajay
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Old   November 26, 2003, 15:46
Default Re: Macro to set Wall Shear Stress
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co2
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so ajay, did you come up with something ?
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