Input_flags

---

---

How to change the amplitude of the initial condition (noise)

The amplitude of the initial condition can be prescribed for the finite-k modes by using --noise-amplitude-k followed by a double precision number. For the horizontally-averaged modes (kx=ky=0), use --noise-amplitude-0 followed by a double. For instance:

mpiexec -n 20 ./coral_LP.exe --noise-amplitude-k 1.d-10 --noise-amplitude-0 3.4d-15

To set both amplitudes to a common value, use --noises-amplitude:

mpiexec -n 20 ./coral_LP.exe --noises-amplitude 1.d-10

---

How to set a different cfl factor along the z-axis.

The optimal timestep dt is computed using the formula

dt = cflFactor * min ( dx/u, dy/v, dz/w)

where cflFactor is defined as parameter 12 in coral.parameters.in. Using the flag --cflFactor-along-z followed by a double precision number, one may define a parameter cflZ such that:

dt = cflFactor * min ( dx/u, dy/v, dz/[w*cflZ] )

For instance:

mpiexec -n 6 ./coral_LP.exe --cflFactor-along-z 0.1d0

yields a cfl criterion that is 10 times larger along the z direction. Note that this correction is multiplicative. Thus, --cflFactor-along-z 1.d0 has no effect.