flat plate simulation using compressible solver

cfdcoder · October 31, 2012, 03:25

I am verifying my compressible solver for laminar flow over flat plate by using Blasius solution. The Reynolds number in such cases is given per length e.g. 5000/metre. My question is - Should I change the value of Reynolds number in my code at every value of X - cordinate over the plate OR should I take the total length of plate I am using as the reference and use the corresponding Reynolds number.

Also in this case should the viscosity be taken as constant or should it be allowed to vary as f(Temperature).

praveen · October 31, 2012, 10:03

It is usually Re based on plate length. The temperature dependance of viscosity is very weak at normal temperatures. So you could use some average temperature that you expect in the solution to compute viscosity used in definition of Re.

cfdcoder · November 2, 2012, 06:32

So if Reynolds number is given as 5000/ metre and I have 2mtr plate then I take Reynolds number constant as 10000 over all the domain. Am I correct here?

I would not be aware of temperature apriori. How can I take average temperature?

praveen · November 2, 2012, 11:39

You must know what Re you want at the end of the plate. Then choose other values to achieve that.

You can use the inflow conditions of temperature, density, etc. to determine Re.

October 31, 2012, 03:25	flat plate simulation using compressible solver	#1
cfdcoder New Member cfdcoder Join Date: Oct 2012 Posts: 2 Rep Power: 0	I am verifying my compressible solver for laminar flow over flat plate by using Blasius solution. The Reynolds number in such cases is given per length e.g. 5000/metre. My question is - Should I change the value of Reynolds number in my code at every value of X - cordinate over the plate OR should I take the total length of plate I am using as the reference and use the corresponding Reynolds number. Also in this case should the viscosity be taken as constant or should it be allowed to vary as f(Temperature).

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October 31, 2012, 10:03		#2
praveen Super Moderator Praveen. C Join Date: Mar 2009 Location: Bangalore Posts: 343 Blog Entries: 6 Rep Power: 18	It is usually Re based on plate length. The temperature dependance of viscosity is very weak at normal temperatures. So you could use some average temperature that you expect in the solution to compute viscosity used in definition of Re.

November 2, 2012, 06:32		#3
cfdcoder New Member cfdcoder Join Date: Oct 2012 Posts: 2 Rep Power: 0	So if Reynolds number is given as 5000/ metre and I have 2mtr plate then I take Reynolds number constant as 10000 over all the domain. Am I correct here? I would not be aware of temperature apriori. How can I take average temperature?

November 2, 2012, 11:39		#4
praveen Super Moderator Praveen. C Join Date: Mar 2009 Location: Bangalore Posts: 343 Blog Entries: 6 Rep Power: 18	You must know what Re you want at the end of the plate. Then choose other values to achieve that. You can use the inflow conditions of temperature, density, etc. to determine Re.