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-   -   CM+5 Convergence of the nonstationary problem (https://www.cfd-online.com/Forums/star-ccm/88619-cm-5-convergence-nonstationary-problem.html)

 ILYA87 May 22, 2011 04:35

CM+5 Convergence of the nonstationary problem

1 Attachment(s)
Vortex pump. Modeling in the star-ccm +5
Since putting the physics of this problem on simple geometry, the pipe, and without some of the physical processes that convergence had the same results, indicating that the first causes of poor convergence is not due to boundary conditions.
And so "the flow of water in the pipe"

Initial conditions:
-Input speed is equal to 0.64 m / sec.
-Pressure in the device 1 atm.
-Outlet pressure of 1 atm.

Physical model:
-Dimensional problem of
-K-E model of turbulence
-The volume of fluid (VOF)
Split-course

Since we solve the nonstationary problem, you must specify the size of the temporary
step and total time. Time will be 5 x 10e-5 (Maximum Physical Time) with the size of the temporary
step 10E-7 (Time-Step), ie require 500 time steps.
Number of cells equal to 640 000.

Turbulent dissipation rate Tdr anywhere behind the convergence of many parameters reached 10e-4, and Tdr 0.1
Thought to help reduce the coefficient of relaxation velocity, but the results are similar.:(

I thought for k-e model: Tdk = 0.001339 Tde = 0.003836, respectively, and the turbulent dissipation rate and turbulent kinetic energy.
for the turbulence model on the scale turbulent velocity 0.036, 0.0021 turbulence scale, turbulence intensity 0.046. (The size of pipe: diameter 0.03 m, length 0.367 m)
The last drawing for the steady.
I am a newbie and probably made stupid mistakes, really need help, because for a long time, no improvement in convergence.

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