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Flow of highly viscous fluid thorugh small annular ring.

Ashish Raman_20688

I am trying to simulate flow between two seperate chambers connected by an annular passage (OD 17mm and ID 14mm) and two orifices of diameter 2.5 mm each (As shown in the sectional view given). I am using a fluid of dynamic viscosity 4.85 Pa.s (kinematic viscosity = 5000 cSt). In the subsequent simulations I have to reduce the thickness of the annular passage to 20 microns. Will HW CFD be able to capture the physics in such low dimensions. Also, how to proceed with the meshing in such cases. Right now I am using laminar flow for the modelling.

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AcuSolve

HyperMesh CFD

v2021

Accepted answers

ydigit

20 microns, is unlikely to work with AcuSolve. You could try though with very fine mesh in that region. Make sure that there are atleast 8 nodes in the thinnest section and ideally 10-15.
Also make sure that there are refinement zones near this orifice.

Ovando_RBB

Hi there,

It is not practical to simulate very small dimensions such as 20 microns because the solver will loose numerical resolution due such a very small floating point numbers; the model will tend to capture only numerical noise and as a consequence hard to find convergency.

Instead, a widely used approach in fluid dynamics and engineering is scalation through Reynolds number where you might need similar Froude number too if your engineering application is sensitive to the gravitational field from earth.

All comments

ydigit

Ovando_RBB

Hi there,

Ashish Raman_20688

Thanks for your insights.

Ashish Raman_20688

Thanks for your insights.