Boundary layer transition problem

hadesmajesty · December 20, 2010, 01:54

I am using DNS to study the boundary layer transition problem. I find in my model, the 3D structures like, lambda vortex, always come up at higher Reynolds number (and correspondingly the waves with higher spanwise wavenumber show weaker amplification), compared with other simulations and experiments.

I am solving 3D vorticity-velocity NS equation with finite difference in downstream and wall-normal directions and spectral method in spanwise direction.

I wonder if anyone has similar experience? What are the possible reasons that may lead to current results?

Thank you.

DoHander · December 21, 2010, 12:54

You need to be sure you use the same initial conditions for your simulation as your reference cases. DNS is very sensitive to small modifications of the initial conditions.

Do

hadesmajesty · December 22, 2010, 00:26

Thank you so much Do.

Your suggestions inspire me. I measured my initial conditions in spectral space and did not notice the differences with experiments.

December 20, 2010, 01:54	Boundary layer transition problem	#1
hadesmajesty Member Edison Join Date: Mar 2009 Posts: 40 Rep Power: 17	I am using DNS to study the boundary layer transition problem. I find in my model, the 3D structures like, lambda vortex, always come up at higher Reynolds number (and correspondingly the waves with higher spanwise wavenumber show weaker amplification), compared with other simulations and experiments. I am solving 3D vorticity-velocity NS equation with finite difference in downstream and wall-normal directions and spectral method in spanwise direction. I wonder if anyone has similar experience? What are the possible reasons that may lead to current results? Thank you.

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December 21, 2010, 12:54		#2
DoHander Senior Member Join Date: Nov 2009 Posts: 411 Rep Power: 19	You need to be sure you use the same initial conditions for your simulation as your reference cases. DNS is very sensitive to small modifications of the initial conditions. Do

December 22, 2010, 00:26		#3
hadesmajesty Member Edison Join Date: Mar 2009 Posts: 40 Rep Power: 17	Thank you so much Do. Your suggestions inspire me. I measured my initial conditions in spectral space and did not notice the differences with experiments.