Upwind Vs Central Difference

saurabh007 · September 22, 2014, 15:02

I discretized an unsteady state convection diffusion equation and solved it with both CDS and upwind scheme and Crank Nicholson time step. But the solution of CDS and upwind are same till certain time interval (exactly speaking till 60 iterations) but after that upwind tends to give wrong solution. Is there something wrong with my code or is it because of less accurate upwind scheme.

Please help.
Thanks in advance.

Wikie · September 26, 2014, 07:26

Hi,

I think this is not the right subforum to discuss this.
Nevertheless upwind scheme shouldn't be used for 3D problems. To check the discretization error it's recommended to run your simulations with different schemes with increasing order as you did. Different results indicating a discretization error and it's recommended to increase the numer of cells and rerun the simulation.

cheers
wikie

September 22, 2014, 15:02	Upwind Vs Central Difference	#1
saurabh007 New Member KUMAR SAURABH Join Date: Sep 2014 Posts: 6 Rep Power: 12	I discretized an unsteady state convection diffusion equation and solved it with both CDS and upwind scheme and Crank Nicholson time step. But the solution of CDS and upwind are same till certain time interval (exactly speaking till 60 iterations) but after that upwind tends to give wrong solution. Is there something wrong with my code or is it because of less accurate upwind scheme. Please help. Thanks in advance.

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September 26, 2014, 07:26		#2
Wikie Member Roman Gobitz-Pfeifer Join Date: Dec 2009 Location: Stuttgart Posts: 83 Rep Power: 16	Hi, I think this is not the right subforum to discuss this. Nevertheless upwind scheme shouldn't be used for 3D problems. To check the discretization error it's recommended to run your simulations with different schemes with increasing order as you did. Different results indicating a discretization error and it's recommended to increase the numer of cells and rerun the simulation. cheers wikie