geometry - 6mm diameter 25mm length
model- vof multiphase
primary phase-air
secondary phase -water
pressure at inlet - zero gauge
pressure at outlet - zero gauge
contact angle -30 degree
wall adhesion on - 73.5 dyne/cm surface tension
implicit body force on
Please check the boundary conditions. Also, look at the capillary pressure- saturation relationship using wetting/scanning curve.
https://www.sciencedirect.com/search?qs=reversal%20of%20flow%20while%20simulating%20capillary%20rise%20in%20fluent&show=25&sortBy=relevance
The program does not count anything by itself. There is a specific algorithm, there is input data. Without the possibility of interference in the program (there is no such option), one can only guess. Regards,
Revers flow always appear in transient flow simulation , mainly two reasons , large Guarant No. or large time step .
Best regards.
Erroneous input data (eg too large integration step) determine incorrect results. It is obvious. But is this a mistake? Regards,
In transient calculations , big step = big in-correct results= revers flow & many other problems including divergence of solution .
You can use variable step technique , adjust both Guarant No. and max. step , then the solution go faster and converge.
Best regards.
This paper
"Dynamics of Capillary Rise" by
B. V. Zhmud,1 F. Tiberg, and K. Hallstensson
Explains about the oscillation of capillary meniscus
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