# Flow Simulation for Laminar Flow in Annular Gap?

Would anyone be able to run an air flow simulation through the following geometry at 100 cc/min? I'm curious if any dead spots occur and if the geometry of the annular gap will produce laminar flow. Dimensions are in inches.

Reynold's number analysis:

Hydraulic Diameter* = 0.003 in = 7.62E-5 m Absolute Viscosity of Air at 20.2C = 1.983E-5 N-s/m^2 Density of Air at 20C = 1.293 kg/m^3 Mean Velocity = => A_cs = 0.004089 cm^2 => Q = 100 cc/min => V = 24455.9 cm/min = 4.076 m/s

Therefore,

Re = (rhoVD)/nu = (1.293 kg/m^3 * 4.076 m/s * 7.62E-5 m) / 1.983E-5 N-s/m^2 Re = 20.25

• Have you thought about calculating to see if you will get laminar flow? Apr 10 '19 at 15:33
• I have and am getting some odd Reynold's numbers. Based on the above geometry and flow rate of 100 cc/min, how would you calculate the Reynold's number? Apr 10 '19 at 17:02
• Show your analysis for the Reynolds number... Apr 10 '19 at 17:04
• I edited the post to reflect my Reynolds number analysis. I think I may be having a fundamental issue with what the cross-sectional area of an annular gap is and/or what to use for the hydraulic diameter. Apr 11 '19 at 18:24
• @SolarMike Any ideas? Apr 12 '19 at 13:34