sandbox/Antoonvh/gaussianvortex.c
A Gaussian vortex
Say,
\displaystyle v_\theta = r e^{-r^2},
Then the centrifugal acceleration is
\displaystyle a_r = \frac{v_\theta^2}{r} = r e^{-2r^2}.
This is balance by the pressure gradient
\displaystyle -\nabla p = a.
Hence,
\displaystyle p = -\frac{1}{4}e^{-2r^2} + C.
Is it true?
set xr [0:2]
set yr [-0.3:0.05]
set grid
set xlabel 'r'
set ylabel 'Pressure'
plot 'pressure', -exp(-2*x**2)/4
Yes…
#include "navier-stokes/centered.h"
#include "profile6.h"
int main() {
L0 = 20;
X0 = Y0 = -L0/2;
N = 256;
run();
}
event init (t = 0) {
TOLERANCE = 1e-6;
foreach() {
u.y[] = x*exp(-(sq(x) + sq(y)));
u.x[] = -y*exp(-(sq(x) + sq(y)));
}
}
event stop (i = 1) {
profile ({p}, sqrt(sq(x) + sq(y)), "pressure");
}