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extreme strange problem about unsteady calculation

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Old   June 27, 2008, 09:12
Default extreme strange problem about unsteady calculation
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I'm doing a unsteady calculation about flow past sphere with an acceleration. We know that when Rep<<1, we could describe this flow using N-S equation without convection term. when the Rep number grows larger than 1 as the time goes by, the calculation results seems also to be dominated by N-S equation without convection term!! it means that no matter Stokes force, history force, or added mass force, all just variate linearly, but actually, it should not. I has already try to vary my time step and magnitude of acceleration, but all of them remain ineffective. Is there anyone who ever met a similar problem? thanks a lot for your concerns some paraments: Vstart=0, a=1e-4, time step=0.01 radius of sphere 5e-3, so rep number variates 0.01 each time step
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Old   June 27, 2008, 09:22
Default Re: extreme strange problem about unsteady calcula
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it just seems that fluent sticks to the initial statement even the rep number is growing. (in addition, I use 2ddp to promise the accuracy)
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