CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Main CFD Forum

Confusion about non-dimensionalization and Reynolds no.

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   June 20, 2011, 10:40
Default Confusion about non-dimensionalization and Reynolds no.
  #1
Senior Member
 
TWB
Join Date: Mar 2009
Posts: 105
Rep Power: 8
quarkz is on a distinguished road
Hi,

I am confused about non-dimensionalization and Reynolds no.

I have a numerical NS solver which uses the non-dimensional NS equation to solve.

I can specify the Re and u_inf values.

Supposed I want to solve the flow past a cylinder.

I let Re = 40, u_inf = 1. I get a steady solution of cd=1.6

If I now change u_inf to 2, my cd becomes around 5.

However, Re is still 40. I thought that if my Re remains the same, I should get the same ans...

Did I miss out something? Or is there something wrong with my solver?

Hope someone can help!
quarkz is offline   Reply With Quote

Old   June 20, 2011, 15:26
Default
  #2
Senior Member
 
morteza08's Avatar
 
Morteza
Join Date: May 2010
Location: Iran,Islamic Republic of
Posts: 159
Rep Power: 7
morteza08 is on a distinguished road
respected friend
I think you are trying to slove a problem that you have not the sufficient knowledge about that.
Non-dimensionalization is one the fundamental course matters in fluid mechanics...
Take a look at some fluid mechanics to get more familiar with this matter.
Explain more about the code...
I can help you........
morteza08 is offline   Reply With Quote

Old   June 20, 2011, 18:11
Default
  #3
Senior Member
 
TWB
Join Date: Mar 2009
Posts: 105
Rep Power: 8
quarkz is on a distinguished road
Hi, I think there's something wrong with my numerical solver.

I tried to run the same case in Fluent. As long as the calculated Re=40, my result will be the same. I can double the velocity from 1 to 2. In that case, to get the same Re, I can maybe half the density. The ans for both will be the same.
quarkz is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 07:08.