How to obtain turbulent K.E. from DNS data?

November 28, 2003, 07:35

There're mean and fluctuating velocities,Reynolds stress budgets,but not turbulent kinetic energy.Should I simply square each fluctuating component and sum up them?

November 29, 2003, 00:15

If you have 9 budgets for 9 reynolds stress components u can add the budgets for diagonal Re-stresses namely the (u^2) bar, (v^2)bar and (w^2)bar budgets and divide by 2 to get turbulent k.e. budget... sorry if it is not that simple...

November 29, 2003, 07:51

But what I want is the distribution of k.

November 29, 2003, 08:10

Oh!I'm sorry!It's rms velocities,not fluctuating velocities.So I can simply square each component and sum up them.

December 15, 2003, 08:18

Hi,

k=(uu+vv+ww)/2

DNS-data commonly gives you the value of each Reynolds stress and hence you just adds the normal-components and divide by two. Check that you have the Reynolds stress (e.g. uu) and not the fluctuating velocity (e.g. u).

/Jonas

December 16, 2003, 06:40

Ah!I got it.Thank you, Jonas!

November 28, 2003, 07:35	How to obtain turbulent K.E. from DNS data?	#1
Boying Lin Guest Posts: n/a	There're mean and fluctuating velocities,Reynolds stress budgets,but not turbulent kinetic energy.Should I simply square each fluctuating component and sum up them?

November 29, 2003, 00:15	Re: How to obtain turbulent K.E. from DNS data?	#2
Subhra Guest Posts: n/a	If you have 9 budgets for 9 reynolds stress components u can add the budgets for diagonal Re-stresses namely the (u^2) bar, (v^2)bar and (w^2)bar budgets and divide by 2 to get turbulent k.e. budget... sorry if it is not that simple...

November 29, 2003, 07:51	Re: How to obtain turbulent K.E. from DNS data?	#3
Boying Lin Guest Posts: n/a	But what I want is the distribution of k.

November 29, 2003, 08:10	Re: How to obtain turbulent K.E. from DNS data?	#4
Boying Lin Guest Posts: n/a	Oh!I'm sorry!It's rms velocities,not fluctuating velocities.So I can simply square each component and sum up them.

December 15, 2003, 08:18	Re: How to obtain turbulent K.E. from DNS data?	#5
Jonas Bredberg Guest Posts: n/a	Hi, k=(uu+vv+ww)/2 DNS-data commonly gives you the value of each Reynolds stress and hence you just adds the normal-components and divide by two. Check that you have the Reynolds stress (e.g. uu) and not the fluctuating velocity (e.g. u). /Jonas

December 16, 2003, 06:40	Re: How to obtain turbulent K.E. from DNS data?	#6
Boying Lin Guest Posts: n/a	Ah!I got it.Thank you, Jonas!

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