[yujin_cfd]

Hello all,

I'm running a simulation with a Reynolds number of 100,000 and encountering an issue with the expected variation of turbulence intensity (TI). I’m using a Realizable k-ε turbulence model with variable turbulent kinetic energy (k) and dissipation rate (ε), controlled via a UDF. My setup includes:

Reynolds number: 100,000
Turbulence model: Realizable k-ε with Menter-Lechner wall treatment
Time steps: 150, each with a 0.1 s step size
Velocity: 1.46 m/s, leading to the specified Reynolds number
The issue is that, when calculating the TI based on the fluctuating values of k and ε, I am expecting an upward variation in the TI values over time. However, the actual trend I am observing is downward. This was quite unexpected, and I was hoping to gain insight into why this might be happening.

Has anyone encountered similar behavior in Fluent or has any thoughts on why the trend could be downward? Is there something I could be missing in my UDF or in how Fluent handles the turbulence variables over time?

Any insights or suggestions would be greatly appreciated!

Thank you.