Help:Finding sources of error

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 July 25, 2005, 21:31 Help:Finding sources of error #1 Quarkz Guest   Posts: n/a Hi, I've written a NS FVM solver. I'm using Ghia's lid driven cavity result to test for accuracy. The u values for the same grid size typically have difference of less than 2%, except one which is different by 20% (0.003 vs 0.004). However, the v values typically have difference of 2-5%. I'm wondering if that is acceptable... I'm trying to find out the source of error. I was thinking of wrong implementation of BC but then my u values will not be so close then. Hence I suspect that there are some careless mistakes in my v,y BC. Is that logical since my v values differs by 2-5%? Thank you very much

 July 26, 2005, 10:00 Re: Help:Finding sources of error #2 M Guest   Posts: n/a Firstly, if You would like to get help here, please give description of Your solver. NS FVM solver rather wide formulation When I had the same problem, I fixed it having found a mistake in high-order discretization schemes of convective terms (there was a bug). With BC there have not to be problems U and V all zero except upper wall where U=1. As a rule on the fine grid (300x300) with HLPA scheme You should obtain excellent results All that from my experience with SIMPLE solver on staggered as well as colocated grids

 July 26, 2005, 10:03 Re: Help:Finding sources of error #3 M Guest   Posts: n/a By the way, how do You get Ghia's velosity distribution?

 August 2, 2005, 04:29 Re: Help:Finding sources of error #4 quarkz Guest   Posts: n/a what do you mean by how to get Ghia's velosity distribution? the velocities are given in his paper in journal of computational physics 1982 48 p387

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