Skin Friction co-efficient (Cf)

Nil · May 22, 2013, 02:24

Hello all,

I need to insert the value of skin friction co-efficient (Cf) into my design [left ventricle of the heart], but I don't know how to input it in ANSYS CFX 14.0. I need to know how to insert the value of Cf in the wall with NO SLIP boundary condition. Any help would be highly appreciated.

Thanks!

ghorrocks · May 22, 2013, 05:54

This will work back to a wall shear stress. So use the wall shear stress boundary and write a CEL expression from your Cf.

Nil · May 22, 2013, 05:58

Thanks mate!

Umm, did you mean WSS in post-processor? Could you please describe how should I do it?

Cheers

ghorrocks · May 22, 2013, 07:22

No, I mean use the "Specified Shear" option when you set the wall boundary condition. THen you can set the wall shear stress at that wall as a function of anything you like.

Nil · May 23, 2013, 06:39

I have got the value of WSS from the equation of Cf, but while inserting it, I am bit confused how to put it here? I have 1 inlet and the rest of the structure is 'wall'. My structure is similar to the cylindrical-shape.

Say I have got the value of WSS of 319.44 N/m2 and how should I put it in this case? WSS won't be same in everywhere of the LV of the heart?

ghorrocks · May 24, 2013, 06:14

Yes, if you enter the WSS as 319 then it will be 319 everywhere. If you want it to vary then you need to make it a function of something which varies.

Nil · May 27, 2013, 04:53

I'm still trying it out. Thank you so much!

May 22, 2013, 02:24	Skin Friction co-efficient (Cf)	#1
Nil New Member Md. Join Date: Dec 2012 Posts: 5 Rep Power: 13	Hello all, I need to insert the value of skin friction co-efficient (Cf) into my design [left ventricle of the heart], but I don't know how to input it in ANSYS CFX 14.0. I need to know how to insert the value of Cf in the wall with NO SLIP boundary condition. Any help would be highly appreciated. Thanks!

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May 22, 2013, 05:54		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,696 Rep Power: 143	This will work back to a wall shear stress. So use the wall shear stress boundary and write a CEL expression from your Cf.

May 22, 2013, 05:58		#3
Nil New Member Md. Join Date: Dec 2012 Posts: 5 Rep Power: 13	Thanks mate! Umm, did you mean WSS in post-processor? Could you please describe how should I do it? Cheers

May 22, 2013, 07:22		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,696 Rep Power: 143	No, I mean use the "Specified Shear" option when you set the wall boundary condition. THen you can set the wall shear stress at that wall as a function of anything you like.

May 23, 2013, 06:39		#5
Nil New Member Md. Join Date: Dec 2012 Posts: 5 Rep Power: 13	I have got the value of WSS from the equation of Cf, but while inserting it, I am bit confused how to put it here? I have 1 inlet and the rest of the structure is 'wall'. My structure is similar to the cylindrical-shape. Say I have got the value of WSS of 319.44 N/m2 and how should I put it in this case? WSS won't be same in everywhere of the LV of the heart?

May 24, 2013, 06:14		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,696 Rep Power: 143	Yes, if you enter the WSS as 319 then it will be 319 everywhere. If you want it to vary then you need to make it a function of something which varies.

May 27, 2013, 04:53		#7
Nil New Member Md. Join Date: Dec 2012 Posts: 5 Rep Power: 13	I'm still trying it out. Thank you so much!