First Coulomb implementation that works
After fixing all possible divisions by zero I was able to find in the Coulomb collision I think that this is a first working implementation of a Coulomb operator based on moments. Still to test a few things, modify the manual but I would say that I'm satisfiyed right now. This operator won't be used that often but maybe improving efficiency is still needed. In the future a binary operator is required to be able to study cases out of Maxwellian equilibrium.
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3 changed files with 51 additions and 26 deletions
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@ -977,6 +977,7 @@ MODULE moduleMesh
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REAL(8):: l2, l, lW, AW
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REAL(8):: deltaV(1:3), totalDeltaV_ij, normDeltaV
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REAL(8):: rnd
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REAL(8):: eps = 1.D-10
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!$OMP DO SCHEDULE(DYNAMIC) PRIVATE(partTemp)
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@ -1011,13 +1012,22 @@ MODULE moduleMesh
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velocity = cell%gatherF(partTemp%part%Xi, cell%nNodes, velocityNodes)
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temperature = cell%gatherF(partTemp%part%Xi, cell%nNodes, temperatureNodes)
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l2 = coulombMatrix(k)%l2_j/temperature
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l = SQRT(l2)
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!If cell temperature is too low, skip particle to avoid division by zero
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IF (temperature>eps) THEN
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l2 = coulombMatrix(k)%l2_j/temperature
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l = SQRT(l2)
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ELSE
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partTemp => partTemp%next
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CYCLE
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END IF
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W = partTemp%part%v - velocity
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normW = NORM2(W)
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IF (normW < 1.D-12) THEN
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!If relative velocity is too low, skip collision and move to next particle
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!If relative velocity is too low, skip collision to avoid division by zero and move to next particle
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IF (normW < eps) THEN
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partTemp => partTemp%next
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CYCLE
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@ -1027,7 +1037,6 @@ MODULE moduleMesh
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lW = l * normW
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AW = coulombMatrix(k)%A_i/normW
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delta_par = -coulombMatrix(k)%A_i*coulombMatrix(k)%one_plus_massRatio_ij*density*l2*G(lW)
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delta_par_square = AW*density*G(lW)
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@ -1063,8 +1072,8 @@ MODULE moduleMesh
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END DO
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!Do scattering of particles from species_j due to species i
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IF (i /= j) THEN
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!Do scattering of particles from species_j due to species i
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!Compute background properties of species_i
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DO n = 1, cell%nNodes
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node => self%nodes(cellNodes(n))%obj
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@ -1072,10 +1081,11 @@ MODULE moduleMesh
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densityNodes(n) = output%density/n_ref
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velocityNodes(n,1:3) = output%velocity(1:3)/v_ref
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temperatureNodes(n) = output%temperature/T_ref
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END DO
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!Divide total momentum exchanged among all the particles of species j
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!TODO: This is a dirty trick to ensure conservation between species
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normDeltaV = totalDeltaV_ij / REAL(cell%listPart_in(j)%amount) * &
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(coulombMatrix(k)%sp_i%weight*coulombMatrix(k)%sp_i%m) / &
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(coulombMatrix(k)%sp_j%weight*coulombMatrix(k)%sp_j%m)
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@ -1087,26 +1097,35 @@ MODULE moduleMesh
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velocity = cell%gatherF(partTemp%part%Xi, cell%nNodes, velocityNodes)
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temperature = cell%gatherF(partTemp%part%Xi, cell%nNodes, temperatureNodes)
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l2 = coulombMatrix(k)%l2_i/temperature
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l = SQRT(l2)
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W = partTemp%part%v - velocity
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normW = NORM2(W)
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IF (normW < 1.D-12) THEN
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!If relative velocity is too low, skip collision and move to next particle
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!If cell temperature is too low, skip particle to avoid division by zero
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IF (temperature>eps) THEN
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l2 = coulombMatrix(k)%l2_i/temperature
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l = SQRT(l2)
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ELSE
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partTemp => partTemp%next
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CYCLE
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END IF
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W = partTemp%part%v - velocity
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normW = NORM2(W)
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!If relative velocity is too low, skip collision and move to next particle
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IF (normW < eps) THEN
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partTemp => partTemp%next
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CYCLE
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END IF
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lW = l * normW
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AW = coulombMatrix(k)%A_j/normW
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delta_par = -coulombMatrix(k)%A_j*coulombMatrix(k)%one_plus_massRatio_ji*density*l2*G(lW)
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delta_par_square = AW*density*G(lW)
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delta_per_square = AW*density*H(lW)
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dW(1) = delta_par*tauMin + randomMaxwellian()*SQRT(delta_par_square*tauMin)
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@ -1114,7 +1133,13 @@ MODULE moduleMesh
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!Normalize with average exchange per particle
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!TODO: This is a dirty trick to ensure conservation between species
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dW = normDeltaV*dW/NORM2(dW)
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IF (NORM2(dW) > eps) THEN
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dW = normDeltaV*dW/NORM2(dW)
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ELSE
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dW = 0.D0
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END IF
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!System of reference for the velocity change
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!First one is parallel to the relative velocity
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@ -1127,24 +1152,24 @@ MODULE moduleMesh
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!Third one is perpendicular to the other two
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e3 = crossProduct(e1, e2)
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e3 = normalize(e3)
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!Random number for direction
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rnd = PI2*random()
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deltaV = dW(1)*e1 + dW(2)*(COS(rnd)*e2 + SIN(rnd)*e3)
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!Change particle velocity
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partTemp%part%v = partTemp%part%v + deltaV
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partTemp => partTemp%next
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END DO
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END IF
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END DO
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DEALLOCATE(densityNodes, velocityNodes, temperatureNodes)
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DEALLOCATE(densityNodes, velocityNodes, temperatureNodes, cellNodes)
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END DO
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!$OMP END DO
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