[Nek5000-users] Finite-amplitude disturbance based on os7000

[nek5000-users at lists.mcs.anl.gov]

Dear Nek users,


I run into a problem when I tried to realize a 2D finite-amplitude disturbance in the plane poiseuille flow (based on example of os7000). The code was compiled successfully and the initial conditions (base + disturbance) were all good (I verified the profiles with the literature). Both of the base flow (u = 1-y^2) and perturbation are set in the useric subroutine.  Periodic boundary condition is employed. one wavelength is simulated.


However, after the simulation starts, the perturbations somehow do not really evolve correctly; the wave shape along the streamwise was somehow distorted especially for the first few time steps (both ux' and uy'). After that, it recovered a bit but never went back to the perfect shape same as that in literature at later time steps. This issue yields some significant discrepancy with the available literature paper. I wonder if this could be due to the non-linear effect. Could anyone help me on this please?


Regards,


Emily
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