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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 REAL(8):: rnd
!$OMP SINGLE
DO e = 1, self%numCells DO e = 1, self%numCells
cell => self%cells(e)%obj cell => self%cells(e)%obj
cellNodes = cell%getNodes(cell%nNodes) cellNodes = cell%getNodes(cell%nNodes)
@ -1016,6 +1017,7 @@ MODULE moduleMesh
lW = l * normW lW = l * normW
AW = coulombMatrix(k)%A_i/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 = -coulombMatrix(k)%A_i*coulombMatrix(k)%one_plus_massRatio_ij*density*l2*G(lW)
delta_par_square = AW*density*G(lW) delta_par_square = AW*density*G(lW)
@ -1050,38 +1052,40 @@ MODULE moduleMesh
IF (i /= j) THEN IF (i /= j) THEN
!Do scattering of particles from species_j due to species i !Do scattering of particles from species_j due to species i
!Compute background properties of species_i
DO n = 1, cell%nNodes DO n = 1, cell%nNodes
node => self%nodes(cellNodes(n))%obj node => self%nodes(cellNodes(n))%obj
CALL calculateOutput(node%output(i), output, node%v, coulombMatrix(k)%sp_i) CALL calculateOutput(node%output(i), output, node%v, coulombMatrix(k)%sp_i)
densityNodes(n) = output%density/n_ref densityNodes(n) = output%density/n_ref
velocityNodes(n,1:3) = output%velocity(1:3)/v_ref velocityNodes(n,1:3) = output%velocity(1:3)/v_ref
temperatureNodes(n) = output%temperature/T_ref temperatureNodes(n) = output%temperature/T_ref
END DO END DO
!Loop over particles of species_j
partTemp => cell%listPart_in(j)%head partTemp => cell%listPart_in(j)%head
DO WHILE(ASSOCIATED(partTemp)) DO WHILE(ASSOCIATED(partTemp))
density = cell%gatherF(partTemp%part%Xi, cell%nNodes, densityNodes) density = cell%gatherF(partTemp%part%Xi, cell%nNodes, densityNodes)
velocity = cell%gatherF(partTemp%part%Xi, cell%nNodes, velocityNodes) velocity = cell%gatherF(partTemp%part%Xi, cell%nNodes, velocityNodes)
temperature = cell%gatherF(partTemp%part%Xi, cell%nNodes, temperatureNodes) temperature = cell%gatherF(partTemp%part%Xi, cell%nNodes, temperatureNodes)
l2 = coulombMatrix(k)%l2_i/temperature l2 = coulombMatrix(k)%l2_i/temperature
l = SQRT(l2) l = SQRT(l2)
W = partTemp%part%v - velocity W = partTemp%part%v - velocity
normW = NORM2(W) normW = NORM2(W)
lW = l * normW lW = l * normW
AW = coulombMatrix(k)%A_j/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 = -coulombMatrix(k)%A_j*coulombMatrix(k)%one_plus_massRatio_ji*density*l2*G(lW)
delta_par_square = AW*density*G(lW) delta_par_square = AW*density*G(lW)
delta_per_square = AW*density*H(lW) delta_per_square = AW*density*H(lW)
dW(1) = delta_par*tauMin + randomMaxwellian()*SQRT(delta_par_square*tauMin) dW(1) = delta_par*tauMin + randomMaxwellian()*SQRT(delta_par_square*tauMin)
dW(2) = ABS(randomMaxwellian()*SQRT(delta_per_square*tauMin)) dW(2) = ABS(randomMaxwellian()*SQRT(delta_per_square*tauMin))
!System of reference for the velocity change !System of reference for the velocity change
!First one is parallel to the relative velocity !First one is parallel to the relative velocity
e1 = normalize(W) e1 = normalize(W)
@ -1093,20 +1097,24 @@ MODULE moduleMesh
!Third one is perpendicular to the other two !Third one is perpendicular to the other two
e3 = crossProduct(e2, e1) e3 = crossProduct(e2, e1)
e3 = normalize(e3) e3 = normalize(e3)
!Random number for direction
rnd = PI2*random() rnd = PI2*random()
!Change particle velocity
partTemp%part%v = partTemp%part%v + dW(1)*e1 + dW(2)*(COS(rnd)*e2 + & partTemp%part%v = partTemp%part%v + dW(1)*e1 + dW(2)*(COS(rnd)*e2 + &
SIN(rnd)*e3) SIN(rnd)*e3)
partTemp => partTemp%next partTemp => partTemp%next
END DO END DO
END IF END IF
END DO END DO
END DO END DO
!$OMP END SINGLE
END SUBROUTINE doCoulomb END SUBROUTINE doCoulomb

2
src/modules/moduleCoulomb.f90
View file

@ -79,7 +79,7 @@ MODULE moduleCoulomb
END SELECT 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_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 self%A_j = 8.D0*PI*Z_j**2*Z_i**2*self%lnCoulomb / self%sp_j%m**2