Finding Transition point over blimp

Light014 · April 20, 2022, 05:22

Hi everyone,

I am relatively new to CFD and I am trying to find the point in which the flow over an blimp transitions from Laminar to Turbulent. I am using the k-omega SST model, and I plotted a contour of the Reynolds using a definition "(density * 20 * x)/viscosity-lam" where 20 ms-1 is the inlet velocity. Unfortunately, it is showing that the Reynolds at the nose -1.27 million Reynolds and the end of the blimp -205k. I tried plotting velocity profiles but it is showing that the flow is going from turbulent to laminar.

Cell quality is good, I have 25 boundary layers where y+ < 1. I am not too sure what I am doing wrong, I have searched around and could not find anything helpful to solve the issues I am having.

AlexanderZ · April 21, 2022, 03:52

you may look for intermittency factor in fluent, It shows transition explicitly

Light014 · April 27, 2022, 14:14

Ah thank you, when plotting the intermittency contour it shows me where transition occurs. I am trying to plot velocity profiles to prove mesh convergence. Since my boundary layer behaves at an angle, i cannot use the z coordinate to plot my velocity profile. is there a way to create a coordinate axis that is normal to the surface using either cfd post or tecplot?

April 21, 2022, 03:52		#2
AlexanderZ Senior Member Alexander Join Date: Apr 2013 Posts: 2,363 Rep Power: 34	you may look for intermittency factor in fluent, It shows transition explicitly __________________ best regards ****************************** press LIKE if this message was helpful

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April 27, 2022, 14:14		#3
Light014 New Member Dawn Join Date: Apr 2022 Posts: 2 Rep Power: 0	Ah thank you, when plotting the intermittency contour it shows me where transition occurs. I am trying to plot velocity profiles to prove mesh convergence. Since my boundary layer behaves at an angle, i cannot use the z coordinate to plot my velocity profile. is there a way to create a coordinate axis that is normal to the surface using either cfd post or tecplot?