[dray19]

Hello,

I am looking the fluid dynamics in a square microchannel for 0.1<=Re<=1000. This involves determining the hydrodynamic entrance length and the friction factor for both in the developing and developed regions.

I have conducted a mesh independent study for Re>100 and validated the results with previous researchers experimental and analytical work

When I did the mesh independent study (7 meshes) for Re=0.1,1,10, inlet pressure increases by 2% (~0.01, 0.1, 1 Pa respectively) with each mesh refinement. The other parameters (velocity, entrance length) seem to constant expect entrance length changed in last few meshes. I increased the number of elements in each direction by 25% to give approximately 2x the number of elements.

Should I keep increasing the mesh? Am I missing something else? I have read (forums) that fluent should be able to handle creep flow but maybe it can't.

Any help is greatly appreciated.

Attached are the results for Re=0.1 mesh study

Model Information:
Microchannel: 100um x 100um x 210um

Model Domain: 50um x 50um x 210um (symmetry applied)
CFD: Ansys Fluent 19.1
Double Precision
Solver - Pressure-Based, Steady State
Model – Laminar
Residual – 10E-6: Continuity, Velocity in X,Y,Z Direction
Methods:
Scheme: SIMPLE
Spatial Discretization
Gradient: Least Squares Cell Based
Pressure: Second Order
Momentum: Second Order Upwind