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Changes to the positining that mainly affects hit and runs to increas…
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…e the success rate of fragmentations after hit and run.
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@daminton
daminton committed Feb 21, 2023
1 parent 5cd7c93 commit abc674a
Showing 1 changed file with 28 additions and 25 deletions.
53 changes: 28 additions & 25 deletions src/fraggle/fraggle_generate.f90
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Original file line number Diff line number Diff line change
Expand Up @@ -326,20 +326,17 @@ module subroutine fraggle_generate_pos_vec(collider, nbody_system, param, lfailu
rdistance = 0.5_DP * sum(impactors%radius(:))
istart = 3
else
rdistance = 2 * impactors%radius(2)
rdistance = impactors%radius(2)
istart = 3
end if

if (lhitandrun) then
mass_rscale(:) = 1.0_DP
else
! Give the fragment positions a random value that is scaled with fragment mass so that the more massive bodies tend to be closer to the impact point
! Later, velocities will be scaled such that the farther away a fragment is placed from the impact point, the higher will its velocity be.
call random_number(mass_rscale)
mass_rscale(:) = (mass_rscale(:) + 1.0_DP) / 2
mass_rscale(:) = mass_rscale(:) * (fragments%mtot / fragments%mass(1:nfrag))**(0.125_DP) ! The power is arbitrary. It just gives the velocity a small mass dependence
mass_rscale(:) = mass_rscale(:) / maxval(mass_rscale(:))
end if
mass_rscale(1:istart-1) = 1.0_DP
! Give the fragment positions a random value that is scaled with fragment mass so that the more massive bodies tend to be closer to the impact point
! Later, velocities will be scaled such that the farther away a fragment is placed from the impact point, the higher will its velocity be.
call random_number(mass_rscale(istart:nfrag))
mass_rscale(istart:nfrag) = (mass_rscale(istart:nfrag) + 1.0_DP) / 2
mass_rscale(istart:nfrag) = mass_rscale(istart:nfrag) * (sum(fragments%mass(istart:nfrag)) / fragments%mass(istart:nfrag))**(0.125_DP) ! The power is arbitrary. It just gives the velocity a small mass dependence
mass_rscale(istart:nfrag) = mass_rscale(istart:nfrag) / minval(mass_rscale(istart:nfrag))

loverlap(:) = .true.
do loop = 1, MAXLOOP
Expand All @@ -353,41 +350,47 @@ module subroutine fraggle_generate_pos_vec(collider, nbody_system, param, lfailu
else ! Keep the first and second bodies at approximately their original location, but so as not to be overlapping
fragment_cloud_center(:,1) = impactors%rcimp(:) - rbuffer * max(fragments%radius(1),impactors%radius(1)) * impactors%y_unit(:)
fragment_cloud_center(:,2) = impactors%rcimp(:) + rbuffer * max(fragments%radius(2),impactors%radius(2)) * impactors%y_unit(:)
fragment_cloud_radius(:) = cloud_size_scale_factor * rdistance
fragments%rc(:,1) = fragment_cloud_center(:,1)
fragments%rc(:,2) = fragment_cloud_center(:,2)
fragment_cloud_radius(:) = rdistance / pack_density
fragments%rc(:,1:2) = fragment_cloud_center(:,1:2)
end if

do i = 1, nfrag
if (loverlap(i)) then
call random_number(phi(i))
call random_number(theta(i))
call random_number(u(i))
phi(i) = TWOPI * phi(i)
theta(i) = asin(2 * theta(i) - 1.0_DP)
end if
end do

! Randomly place the n>2 fragments inside their cloud until none are overlapping
do concurrent(i = istart:nfrag, loverlap(i))
j = fragments%origin_body(i)

! Make a random cloud
phi(i) = TWOPI * phi(i)
theta(i) = acos(2 * theta(i) - 1.0_DP)

! Scale the cloud size
fragments%rmag(i) = fragment_cloud_radius(j) * mass_rscale(i) * u(i)**(THIRD)
if (lhitandrun) then
fragments%rmag(i) = fragment_cloud_radius(j) * u(i)**(THIRD)
else
fragments%rmag(i) = fragment_cloud_radius(j) * mass_rscale(i) * u(i)**(THIRD)
end if

! Position the fragment in a random point within the cloud
fragments%rc(1,i) = fragments%rmag(i) * sin(theta(i)) * cos(phi(i))
fragments%rc(2,i) = fragments%rmag(i) * sin(theta(i)) * sin(phi(i))
fragments%rc(3,i) = fragments%rmag(i) * cos(theta(i))

! Shift to the cloud center coordinates
fragments%rc(:,i) = fragments%rc(:,i) + fragment_cloud_center(:,j)

! Stretch out the hit and run cloud along the flight trajectory
if (lhitandrun) then
fragments%rc(:,i) = fragments%rc(:,i) + cloud_size_scale_factor * rdistance * u(i) * impactors%bounce_unit(:)
fragments%rc(:,i) = fragments%rc(:,i) * (1.0_DP + fragment_cloud_radius(j) * mass_rscale(i) * impactors%bounce_unit(:))
end if

fragments%rc(:,i) = fragments%rc(:,i) + fragment_cloud_center(:,j)

if (lhitandrun) then
fragments%rc(:,i) = fragments%rc(:,i) + (fragment_cloud_radius(j) + maxval(mass_rscale)) * impactors%bounce_unit(:) ! Shift the stretched cloud downrange
else
! Make sure that the fragments are positioned away from the impact point
direction = dot_product(fragments%rc(:,i) - impactors%rcimp(:), fragment_cloud_center(:,j) - impactors%rcimp(:))
Expand Down Expand Up @@ -549,7 +552,7 @@ module subroutine fraggle_generate_vel_vec(collider, nbody_system, param, lfailu
real(DP) :: vmax_guess
integer(I4B), parameter :: MAXLOOP = 25
integer(I4B), parameter :: MAXTRY = 10
integer(I4B), parameter :: MAXANGMTM = 1000
integer(I4B), parameter :: MAXANGMTM = 30000
class(collision_fraggle), allocatable :: collider_local
character(len=STRMAX) :: message

Expand Down Expand Up @@ -682,11 +685,11 @@ module subroutine fraggle_generate_vel_vec(collider, nbody_system, param, lfailu
if (all(dL_metric(:) <= 1.0_DP)) exit angmtm

do i = istart, fragments%nbody
dL(:) = -L_residual(:) * fragments%mass(i) / sum(fragments%mass(istart:fragments%nbody))
dL(:) = -L_residual(:) * fragments%mass(i) / sum(fragments%mass(istart:fragments%nbody))
call collision_util_velocity_torque(dL, fragments%mass(i), fragments%rc(:,i), fragments%vc(:,i))
call collision_util_shift_vector_to_origin(fragments%mass, fragments%vc)
fragments%vmag(i) = .mag.fragments%vc(:,i)
end do
call collision_util_shift_vector_to_origin(fragments%mass, fragments%vc)
fragments%vmag(:) = .mag.fragments%vc(:,:)
end do angmtm

call collision_util_shift_vector_to_origin(fragments%mass, fragments%vc)
Expand Down

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