JGonzalez/fpakc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Trying to implement Lemos Coulomb Scatering

Browse source 
I was having tones of issues with the previous implementation. I think
the problem was the velocity vector and how it was returning to the
normal reference frame.

I hope this new implementation works better.
This commit is contained in:
Jorge Gonzalez 2023-07-11 07:51:49 +02:00
commit d75af4bda7
1 changed files with 20 additions and 29 deletions
Download patch file Download diff file Expand all files Collapse all files

47
src/modules/mesh/moduleMesh.f90
View file

@ -973,9 +973,12 @@ MODULE moduleMesh
REAL(8):: density, velocity(1:3), temperature!values at particle position REAL(8):: density, velocity(1:3), temperature!values at particle position
REAL(8), DIMENSION(1:3):: e1, e2, e3 REAL(8), DIMENSION(1:3):: e1, e2, e3
REAL(8):: delta_par, delta_par_square, delta_per, delta_per_square REAL(8):: delta_par, delta_par_square, delta_per, delta_per_square
REAL(8):: W(3), dW(2), normW !Relative velocity between particle and species and its increment REAL(8):: normW
REAL(8):: l2, l, lW, AW REAL(8):: l2, l, lW, AW, AW2, AW3
REAL(8):: deltaV(1:3) REAL(8):: deltaW, deltaThe, deltaPhi
REAL(8):: cosDeltaPhi, sinDeltaPhi
REAL(8):: cosDeltaThe, sinDeltaThe
REAL(8):: deltaV(1:3) !Relative particle velocity increment
REAL(8):: rnd REAL(8):: rnd
REAL(8):: eps = 1.D-10 REAL(8):: eps = 1.D-10
@ -1023,8 +1026,7 @@ MODULE moduleMesh
END IF END IF
W = partTemp%part%v - velocity normW = NORM2(partTemp%part%v - velocity)
normW = NORM2(W)
!If relative velocity is too low, skip collision to avoid division by zero and move to next particle !If relative velocity is too low, skip collision to avoid division by zero and move to next particle
IF (normW < eps) THEN IF (normW < eps) THEN
@ -1036,32 +1038,21 @@ MODULE moduleMesh
lW = l * normW lW = l * normW
AW = coulombMatrix(k)%A_i/normW AW = coulombMatrix(k)%A_i/normW
AW2 = coulombMatrix(k)%A_i/normW**2 / 2.D0
AW3 = coulombMatrix(k)%A_i/normW**3 / 2.D0
delta_par = -coulombMatrix(k)%A_i*coulombMatrix(k)%one_plus_massRatio_ij*density*l2*G(lW) deltaW = (-coulombMatrix(k)%A_i*coulombMatrix(k)%one_plus_massRatio_ij*l2*G(lW) - AW2*G(lW) + AW2*ERF(lw)) * tauMin + &
SQRT(AW * G(lW) * tauMin) * ABS(randomMaxwellian())
deltaThe = SQRT(2.D0 * AW3 * H(lW) * tauMin)*ABS(randomMaxwellian())
deltaPhi = PI2 * random()
delta_par_square = AW*density*G(lW) cosDeltaThe = COS(deltaThe)
sinDeltaThe = SIN(deltaThe)
cosDeltaPhi = COS(deltaPhi)
sinDeltaPhi = SIN(deltaPhi)
delta_per_square = AW*density*H(lW) !Rotate velocity frame assuming theta = phi = 0
deltaV = (normW + deltaW) * (/ sinDeltaThe * cosDeltaPhi, sinDeltaThe * sinDeltaPhi, cosDeltaPhi /)
dW(1) = delta_par*tauMin + randomMaxwellian()*SQRT(delta_par_square*tauMin)
dW(2) = ABS(randomMaxwellian()*SQRT(delta_per_square*tauMin))
!System of reference for the velocity change
!First one is parallel to the relative velocity
e1 = normalize(W)
!Second one is perpendicular to it
e2(1) = -e1(2)
e2(2) = e1(1)
e2(3) = 0.D0
e2 = normalize(e2)
!Third one is perpendicular to the other two
e3 = crossProduct(e1, e2)
e3 = normalize(e3)
!Random number for direction
rnd = PI2*random()
deltaV = dW(1)*e1 + dW(2)*(COS(rnd)*e2 + SIN(rnd)*e3)
!Change particle velocity !Change particle velocity
partTemp%part%v = partTemp%part%v + deltaV partTemp%part%v = partTemp%part%v + deltaV