Few cells with high Courant

Svensen · February 26, 2017, 13:32

Hi,

during the computation I've found that one or two cells produces a very high Courant number in comparison with the neighbour cells. It may be 100 or even more times higher.

So the question is: does anybody know what to do with such cells or how this problem can be overcame ?

Thanks

piu58 · February 26, 2017, 14:28

You have the highest Co numbers at regions with a high velocity of the fluid through small cells. If this region is not of special interest for you: Make them larger. If it the area you are interested it: Accept the Co number and its implications.

Svensen · February 26, 2017, 14:41

It is clear.

But the problem is that I have a small cells before/after/around the problematic cells but Courant is the neighbouring cells is much less the in these particular 2-3 cells

piu58 · February 27, 2017, 00:13

May you post a graphic or at least sketch of your problem / mesh?

February 26, 2017, 13:32	Few cells with high Courant	#1
Svensen Senior Member Join Date: Jan 2015 Posts: 150 Rep Power: 11	Hi, during the computation I've found that one or two cells produces a very high Courant number in comparison with the neighbour cells. It may be 100 or even more times higher. So the question is: does anybody know what to do with such cells or how this problem can be overcame ? Thanks

February 26, 2017, 14:28		#2
piu58 Senior Member Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15	You have the highest Co numbers at regions with a high velocity of the fluid through small cells. If this region is not of special interest for you: Make them larger. If it the area you are interested it: Accept the Co number and its implications. __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

February 27, 2017, 00:13		#4
piu58 Senior Member Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15	May you post a graphic or at least sketch of your problem / mesh? __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

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February 26, 2017, 14:41		#3
Svensen Senior Member Join Date: Jan 2015 Posts: 150 Rep Power: 11	It is clear. But the problem is that I have a small cells before/after/around the problematic cells but Courant is the neighbouring cells is much less the in these particular 2-3 cells