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No progress in fixing Coulomb collisions with mass ratio

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I am starting to think that the only fix is to reduce the time step, but
that is too harsh.
This commit is contained in:
Jorge Gonzalez 2023-03-07 10:10:54 +01:00
commit f8af7a8dae
2 changed files with 22 additions and 14 deletions
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34
src/modules/mesh/moduleMesh.f90
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@ -978,6 +978,7 @@ MODULE moduleMesh
REAL(8):: rnd
!$OMP SINGLE
DO e = 1, self%numCells
cell => self%cells(e)%obj
cellNodes = cell%getNodes(cell%nNodes)
@ -1016,6 +1017,7 @@ MODULE moduleMesh
lW = l * normW
AW = coulombMatrix(k)%A_i/normW
delta_par = -coulombMatrix(k)%A_i*coulombMatrix(k)%one_plus_massRatio_ij*density*l2*G(lW)
delta_par_square = AW*density*G(lW)
@ -1050,38 +1052,40 @@ MODULE moduleMesh
IF (i /= j) THEN
!Do scattering of particles from species_j due to species i
!Compute background properties of species_i
DO n = 1, cell%nNodes
node => self%nodes(cellNodes(n))%obj
CALL calculateOutput(node%output(i), output, node%v, coulombMatrix(k)%sp_i)
densityNodes(n) = output%density/n_ref
velocityNodes(n,1:3) = output%velocity(1:3)/v_ref
temperatureNodes(n) = output%temperature/T_ref
END DO
!Loop over particles of species_j
partTemp => cell%listPart_in(j)%head
DO WHILE(ASSOCIATED(partTemp))
density = cell%gatherF(partTemp%part%Xi, cell%nNodes, densityNodes)
velocity = cell%gatherF(partTemp%part%Xi, cell%nNodes, velocityNodes)
temperature = cell%gatherF(partTemp%part%Xi, cell%nNodes, temperatureNodes)
l2 = coulombMatrix(k)%l2_i/temperature
l = SQRT(l2)
W = partTemp%part%v - velocity
normW = NORM2(W)
lW = l * normW
AW = coulombMatrix(k)%A_j/normW
delta_par = -coulombMatrix(k)%A_j*coulombMatrix(k)%one_plus_massRatio_ji*density*l2*G(lW)
delta_par_square = AW*density*G(lW)
delta_per_square = AW*density*H(lW)
dW(1) = delta_par*tauMin + randomMaxwellian()*SQRT(delta_par_square*tauMin)
dW(2) = ABS(randomMaxwellian()*SQRT(delta_per_square*tauMin))
!System of reference for the velocity change
!First one is parallel to the relative velocity
e1 = normalize(W)
@ -1093,20 +1097,24 @@ MODULE moduleMesh
!Third one is perpendicular to the other two
e3 = crossProduct(e2, e1)
e3 = normalize(e3)
!Random number for direction
rnd = PI2*random()
!Change particle velocity
partTemp%part%v = partTemp%part%v + dW(1)*e1 + dW(2)*(COS(rnd)*e2 + &
SIN(rnd)*e3)
partTemp => partTemp%next
END DO
END IF
END DO
END DO
!$OMP END SINGLE
END SUBROUTINE doCoulomb

2
src/modules/moduleCoulomb.f90
View file

@ -79,7 +79,7 @@ MODULE moduleCoulomb
END SELECT
self%lnCoulomb = 12.0 !Make this function dependent
self%lnCoulomb = 10.0 !Make this function dependent
self%A_i = 8.D0*PI*Z_i**2*Z_j**2*self%lnCoulomb / self%sp_i%m**2
self%A_j = 8.D0*PI*Z_j**2*Z_i**2*self%lnCoulomb / self%sp_j%m**2