[FLASH-USERS] Internal energy is not reaching statistical steady state in StirTurb (homogeneous isotropic turbulence) problem

[Alam Shadab TU Ilmenau]

Hi,

I am simulating homogeneous isotropic turbulence with stir forcing. I am facing a challenge that the internal energy is not reaching to statistical steady state no matter how small the energy supply rate is. On the other hand, the kinetic energy has reached steady state. Following are the plots of these quantities:

[cid:1093ed08-0703-4a08-9f51-5f31c6f9b1b1]
[cid:35aff225-b892-48f8-ab54-2fb0a75bf7a8]
input parameters for this run are:

energy input - 1e-4 per mode (around 100 modes are stirred)

kinematic viscosity: 0.1

diffusivity: 0.1

grid: 128^3


I simulated the Stirturb problem for many other input parameters using split and unsplit methods, but I am getting the similar trend for the energies.


What am I missing because of which the internal energy is keep on increasing? Could anyone please help me with this?


Best regards,

Shadab

Technische Universität Ilmenau, Germany

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