Aerodynamic coefficients for a flat plate (free molecular flow)
[res1, res2, ...] = CL_mod_aeroPanelCoefV(vel_wind, normal, temp, temp_p, m_mol_mass, ratio_spec, alpha, nsides, res)
Computes aerodynamic coefficients for a flat plate in free molecular flow regime.
The computed quantities (described by the res argument) are:
- cx: drag coefficient (1xN)
- cz: lift coefficient (1xN)
- acv: aerodynamic coefficients vector - drag + lift (3xN)
- acvx: aerodynamic coefficients vector - drag only (3xN)
- acvz: aerodynamic coefficients vector - lift only (3xN)
acv (resp. acvx, acvz) is a vector in the direction of the aerodynamic force F exerted by the wind on the plate:
F = 1/2 * rho * area * ||vel_wind||^2 * acv
where:
- rho is the atmospheric density
- area is the area of the plate
- vel_wind is the wind velocity vector relative to the plate
nsides specifies if only one side of the plate is considered or if both sides are. If nsides is equal to 1, the computed coefficients only take into account the effect of the wind on the side defined by normal. If nsides is equal to 2, the effects of the wind on both sides are considered.
For the meaning of other arguments, see CL_mod_aeroPanelCoef.
Notes:
- The velocity vector (vel_wind) is the velocity vector of the wind relative to the plate.
- The coordinates frame can be any frame. The origin of the frame does not matter.
- The normal vector may not be a unit vector.
- The aerodynamic coefficients vectors (acv, acvx, acvz) have components in the same coordinates frame as vel_wind and normal.
- By definition, acv is the same as acvx + acvz.
- If the effect of lift is neglected, the aerodynamic coefficients vector can be computed by: acv = acvx = cx * vel_wind / ||vel_wind||.
Wind velocity vector (velocity relative to the plate) [m/s]. (3xN or 3x1)
Normal vector to the flat plate defining the reference side. (3xN or 3x1)
Atmospheric temperature [K]. (1x1 or 1xN)
Temperature of the flat plate (wall) [K]. (1x1 or 1xN)
Mean molar mass of incident flow molecules [kg/mol]. (1x1 or 1xN)
Ratio of number of molecules re-emitted specularly (between 0 and 1). (1x1 or 1xN)
Accommodation coefficient. It must be between 0 and 1. (1x1 or 1xN)
(integer) Number of sides to be considered: 1 or 2. (1x1 or 1xN)
Names of computed quantities. (1xP)
Computed quantities. (1xN or 3xN)
CNES - DCT/SB
// vel_wind = wind velocity vector relative to the plate vel_wind = [-7000; 0; 0]; // ang = angle between normal and -vel_wind ang = CL_deg2rad(0 : 180); normal = [cos(ang); zeros(ang); sin(ang)]; temp = 1100; // K temp_p = 300; // K m_mol_mass = 0.015; // kg ratio_spec = 0.1; alpha = 1; // Drag/lift coefficients - one side [cx, cz] = CL_mod_aeroPanelCoefV(vel_wind, normal, temp, temp_p, m_mol_mass, ratio_spec, alpha, 1, ["cx", "cz"]); scf(); plot(CL_rad2deg(ang), cx, "r"); plot(CL_rad2deg(ang), cz, "b"); CL_g_legend(gca(), ["cx", "cz"]); // Aerodynamic coefficients vector - two sides - drag + lift aero_vec = CL_mod_aeroPanelCoefV(vel_wind, normal, temp, temp_p, m_mol_mass, ratio_spec, alpha, 2, "acv"); scf(); plot(CL_rad2deg(ang), aero_vec(1,:), "r"); plot(CL_rad2deg(ang), aero_vec(2,:), "g"); plot(CL_rad2deg(ang), aero_vec(3,:), "b"); CL_g_legend(gca(), ["x", "y", "z"]); | ![]() | ![]() |