Restricting embed_force() Calculations to Specific Boundaries
alessandr...@gmail.com
Dear all,
I am simulating 2D flow past a cylinder (of diameter D) inside a rectangular channel with a height of Ly = 4.1 * D. I am using the embed.h library to define the domain, treating both the upper and lower no-slip channel walls and the cylinder surface as embedded boundaries:
vertex scalar phi[];
foreach_vertex() {
phi[] = intersection (2.05*my_D - y, 2.05*my_D + y);
phi[] = intersection (phi[], sq(x) + sq(y) - sq(0.5*my_D));
}
boundary ({phi});
fractions (phi, cs, fs);
To compute the lift and drag forces on the cylinder, I use the embed_force() function as follows:
event my_logfile (i+=2000) {
coord Fp, Fmu;
embed_force (p, u, mu, &Fp, &Fmu);
fprintf (stderr, "%d %g %g %.6f %.6f %.6f %.6f\n",
i, t, dt, Fp.x, Fp.y, Fmu.x, Fmu.y);
}
The issue I’m encountering is that embed_force() seems to include the contributions from all the embed boundaries—i.e., both the cylinder surface and the channel walls. As a result, the computed forces, particularly the friction drag (Fmu.x), are significantly higher than those reported in the literature, likely due to the inclusion of wall friction.
My question is:
Is there an easy way to restrict the force calculations using embed_force() to only a specific embed boundary (e.g., the cylinder surface), excluding others like the channel walls?
Thank you in advance for your help.
Best regards,
Alessandro
