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What Comsol module would be best for modeling the force from solar radiation pressure on a solar sail?

Posted Sep 22, 2017, 3:48 p.m. EDT Charged Particle Tracing, Ray Optics, Wave Optics Version 5.1 2 Replies

D. C.
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The equation for the force from the reflection and absorption of photons from the sail on a flat square sail is:

The is the incident solar radiation direction, is the normal vector from the sail, is the diffuse reflection coefficient, is the specular reflection coefficient, is the absorption coefficient, is the solar radiation pressure, is the area of the sail. The 's come from the absorption of the solar radiation, and they are the surface emissivity, with the subscripts b and f referring to the back and front side of the sail. The comes from the diffuse reflection of the solar radiation, and is the non-lambertian coefficient, with the subscripts b and f referring to the front and back side of the sail.

To start, I am just trying to find the force vectors on a flat square sail, but eventually I would also like to be able to calculate torque as well. I would also like to be able to use a non-flat sail and vary the angle of incidence.

2 Replies Last Post Sep 25, 2017, 10:25 p.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 7 years ago Sep 23, 2017, 2:20 a.m. EDT
Updated: 7 years ago Sep 23, 2017, 2:21 a.m. EDT

Hi

I believe you need only the standard COMSOL module and the default "Solid" part physics, perhaps the MBD module could simplify a little but then you need both full "Solid and MBD" physics.

Your equation mus be rewriten in the integral form and as a pressure over the area A:

p[Pa] = F[N]/(A[m^2])

and into the three scalar equations (px, py, pz), as COMSOL does not (yet !?) have a full tensor interpreter/parser.

The sun position gives the incident vector n, your geoemtry the sail normal ns for which you would need to define "up and down" directions. Check the doc for the default COMSOL variable definitions for the surface normals (nx, ny, nz) ...

Some of your variables alpha, rho, B might have a directional component (dependent on n * ns too).

Good luck Ivar

-------------------
Have fun COMSOLing,
Sincerely,
Ivar
Hi I believe you need only the standard COMSOL module and the default "*Solid*" part physics, perhaps the *MBD* module could simplify a little but then you need both full "*Solid* and *MBD*" physics. Your equation mus be rewriten in the integral form and as a pressure over the area A: ***p[Pa] = F[N]/(A[m^2])*** and into the three scalar equations ***(px, py, pz)***, as COMSOL does not (yet !?) have a full tensor interpreter/parser. The sun position gives the incident vector ***n***, your geoemtry the sail normal ***ns*** for which you would need to define "up and down" directions. Check the doc for the default COMSOL variable definitions for the surface normals ***(nx, ny, nz)*** ... Some of your variables alpha, rho, B might have a directional component (dependent on ***n * ns*** too). Good luck Ivar
D. C.
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Posted: 7 years ago Sep 25, 2017, 10:25 p.m. EDT

Thank you very much, that was a big help

Thank you very much, that was a big help

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