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Merged
Dhueper merged 3 commits into from
Jul 31, 2025
Merged

Adaptive Time Step - Multi Level RK compatibility #269

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593cae7
Adaptive Time Step - Multi Level RK compatibility
Dhueper Jul 31, 2025
3f5b9af
Minor fix
Dhueper Jul 31, 2025
81a62d4
Minor fix
Dhueper Jul 31, 2025
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8 changes: 5 additions & 3 deletions Solver/src/libs/mesh/HexElementClass.f90
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Expand Up @@ -66,8 +66,9 @@ Module ElementClass
INTEGER :: nodeIDs(8)
integer :: faceIDs(6)
integer :: faceSide(6)
integer :: MLevel ! RK Level
real(kind=RP) :: ML_CFL ! CFL storage for Multi Level RK
integer :: MLevel ! RK Level
real(kind=RP) :: ML_CFL ! CFL storage for Multi Level RK
real(kind=RP) :: ML_error_ratio ! Ratio between temporal and spatial error relative to the global ratio
INTEGER, DIMENSION(3) :: Nxyz ! Polynomial orders in every direction (Nx,Ny,Nz)
real(kind=RP) :: hn ! Ratio of size and polynomial order
TYPE(MappedGeometry) :: geom
Expand Down Expand Up @@ -124,7 +125,8 @@ SUBROUTINE HexElement_Construct( self, Nx, Ny, Nz, nodeIDs, eID, globID)
self % boundaryName = emptyBCName
self % hasSharedFaces = .false.
self % NumberOfConnections = 0
self % MLevel = 1
self % MLevel = 1
self % ML_error_ratio = 1.0_RP
!
! ----------------------------------------
! Solution Storage is allocated separately
Expand Down
36 changes: 26 additions & 10 deletions Solver/src/libs/timeintegrator/AdaptiveTimeStepClass.f90
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Expand Up @@ -101,22 +101,23 @@ end subroutine adaptiveTimeStep_Destruct
! -----------------------------------------------
subroutine adaptiveTimeStep_Update(this, mesh, t, dt)
implicit none
class(adaptiveTimeStep_t) , intent(inout) :: this
class(HexMesh) , intent(in) :: mesh
real(kind=RP) , intent(in) :: t
real(kind=RP) , intent(inout) :: dt
class(adaptiveTimeStep_t) , intent(inout) :: this
class(HexMesh) , intent(inout) :: mesh
real(kind=RP) , intent(in) :: t
real(kind=RP) , intent(inout) :: dt
!! ---------------
! Local variables
!! ---------------
integer :: eID, ierr, i
real(kind=RP) :: dt_weight, sum_dt_weight, dt_lim, min_dt_lim, max_dt_lim
real(kind=RP) :: dt_weight, sum_dt_weight, avg_sum_dt_weight, dt_lim, min_dt_lim, max_dt_lim

min_dt_lim = 0.5_RP ! Minimum limit for the time step
max_dt_lim = 1.3_RP ! Maximum limit for the time step

this % lastAdaptationTime = t
dt_weight = 0.0_RP
sum_dt_weight = 0.0_RP
avg_sum_dt_weight = 0.0_RP
!$omp parallel shared(dt_weight, mesh, this)
!$omp do reduction(+:dt_weight) schedule(runtime)
do eID = 1, mesh % no_of_elements
Expand All @@ -133,10 +134,18 @@ subroutine adaptiveTimeStep_Update(this, mesh, t, dt)
sum_dt_weight = dt_weight
end if

avg_sum_dt_weight = sum_dt_weight / mesh % no_of_allElements

!$omp parallel do schedule(runtime)
do eID = 1, mesh % no_of_elements
mesh % elements(eID) % ML_error_ratio = mesh % elements(eID) % ML_error_ratio / avg_sum_dt_weight
end do
!$omp end parallel do

if (isnan(sum_dt_weight)) then
this % dt_eps(3) = 1e-10_RP
else
this % dt_eps(3) = 1.0_RP / max(sqrt(sum_dt_weight / mesh % no_of_allElements), 1e-10_RP)
this % dt_eps(3) = 1.0_RP / max(sqrt(avg_sum_dt_weight), 1e-10_RP)
end if

if ((this % dt_eps(1) == this % dt_eps(2)) .and. (this % dt_eps(2) == 1.0_RP)) then
Expand Down Expand Up @@ -208,9 +217,9 @@ end subroutine AdaptiveTimeStep_Update

function adaptiveTimeStep_ComputeWeights(this, e) result(dt_weight)
implicit none
class(adaptiveTimeStep_t), intent(in) :: this
type(Element) , intent(in) :: e
real(kind=RP) :: dt_weight
class(adaptiveTimeStep_t), intent(in) :: this
type(Element) , intent(inout) :: e
real(kind=RP) :: dt_weight
!! ---------------
integer :: i, j, k, dir, Ndir
integer :: Pxyz(3)
Expand All @@ -220,7 +229,7 @@ function adaptiveTimeStep_ComputeWeights(this, e) result(dt_weight)
! Initialization of P
Pxyz = e % Nxyz

Ndir = 7 !Number of available error variables
Ndir = 3

dt_weight = 0.0_RP

Expand All @@ -247,6 +256,10 @@ function adaptiveTimeStep_ComputeWeights(this, e) result(dt_weight)
Q_error(k, j, i) = e % storage % QNS(IMP,k,j,i)
QLowRK_error(k, j, i) = e % storage % QLowRK(IMP,k,j,i)
#endif
else if (this % error_variable == 8) then
!Density
Q_error(k, j, i) = e % storage % Q(1,k,j,i)
QLowRK_error(k, j, i) = e % storage % QLowRK(1,k,j,i)
end if
end if
end do
Expand All @@ -257,6 +270,9 @@ function adaptiveTimeStep_ComputeWeights(this, e) result(dt_weight)

dt_weight = dt_weight / (e % storage % sensor)**2.0_RP
dt_weight = dt_weight / ((Pxyz(1)+1) * (Pxyz(2)+1) * (Pxyz(3)+1)) !Average over all Gauss points
! MLRK correction
dt_weight = dt_weight / (3.0_RP ** (e % MLevel - 1))**2.0_RP
e % ML_error_ratio = dt_weight
#endif
end function adaptiveTimeStep_ComputeWeights

Expand Down
31 changes: 25 additions & 6 deletions Solver/src/libs/timeintegrator/ExplicitMethods.f90
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Expand Up @@ -1529,10 +1529,18 @@ SUBROUTINE TakeMLRK3Step( mesh, particles, t, deltaT, ComputeTimeDerivative, dt_



INTEGER :: i, j, id, lID, locLevel, k2, k3, k1, nLevel
INTEGER :: i, j, id, lID, locLevel, k2, k3, k1, nLevel
INTEGER, ALLOCATABLE :: k(:)
REAL(KIND=RP) :: deltaStep(3), corrector, deltaTLF
REAL(KIND=RP), ALLOCATABLE :: cL(:) , tk(:), deltaTL(:) !
REAL(KIND=RP), ALLOCATABLE :: cL(:) , tk(:), deltaTL(:)

logical :: updateQLowRK

if (present(dtAdaptation)) then
updateQLowRK = dtAdaptation
else
updateQLowRK = .false.
end if

nLevel = mesh % MLRK % maxLevel
allocate(k(nLevel), cL(nLevel), tk(nLevel), deltaTL(nLevel))
Expand All @@ -1543,8 +1551,8 @@ SUBROUTINE TakeMLRK3Step( mesh, particles, t, deltaT, ComputeTimeDerivative, dt_
d(3)=1.0_RP/4.0_RP

deltaStep(1) = b(2)
deltaStep(2) = b(3)-b(2)
deltaStep(3) = 1.0_RP-b(3)
deltaStep(2) = b(3)-b(2)
deltaStep(3) = 1.0_RP-b(3)

deltaTL(:) = deltaT
tk(:) = t
Expand All @@ -1553,8 +1561,19 @@ SUBROUTINE TakeMLRK3Step( mesh, particles, t, deltaT, ComputeTimeDerivative, dt_

k(:) = 3
do k1 = 1,3
tk(:) = t + b(k1)*deltaT
call ComputeTimeDerivative( mesh, particles, tk(1), CTD_IGNORE_MODE)
tk(:) = t + b(k1)*deltaT
call ComputeTimeDerivative( mesh, particles, tk(1), CTD_IGNORE_MODE)

if (k1==1 .and. updateQLowRK) then !For adaptive time step only, update QLowRK
!$omp parallel do schedule(runtime)
do id = 1, SIZE( mesh % elements )
#ifdef FLOW
mesh % elements(id) % storage % QLowRK = mesh % elements(id) % storage % Q + deltaT*mesh % elements(id) % storage % QDot
#endif
end do ! id
!$omp end parallel do
end if

locLevel = 1
! -------------------------------------------------------------------------------------------------------------------------------
! LEVEL 2-LEVEL N-1
Expand Down
12 changes: 10 additions & 2 deletions Solver/src/libs/timeintegrator/TimeIntegrator.f90
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Expand Up @@ -140,14 +140,22 @@ SUBROUTINE constructTimeIntegrator(self,controlVariables, sem, initial_iter, ini
self % dt = controlVariables % doublePrecisionValueForKey("dt")
else
self % dt = 1e-8_RP
write(STD_OUT,*) "Warning: 'dt' keyword not specified for adaptive dt. Using initial minimum value of ", self % dt
if (MPI_Process % isRoot ) then
write(STD_OUT,*) "Warning: 'dt' keyword not specified for adaptive dt. Using initial minimum value of ", self % dt
end if
end if
if ( controlVariables % ContainsKey("explicit method") ) then
keyword = controlVariables % StringValueForKey("explicit method",LINE_LENGTH)
call toLower(keyword)
select case (keyword)
case(RK3_NAME)
write(STD_OUT,*) "Using 'RK3' method with adaptive dt."
if (MPI_Process % isRoot ) then
write(STD_OUT,*) "Using 'RK3' method with adaptive dt."
end if
case(ML_RK3_NAME)
if (MPI_Process % isRoot ) then
write(STD_OUT,*) "Using 'ML-RK3' method with adaptive dt."
end if
case default
error stop "Error, only 'RK3' method is implemented for adaptive dt"
end select
Expand Down
1 change: 1 addition & 0 deletions Solver/src/libs/timeintegrator/pAdaptationClass.f90
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Expand Up @@ -482,6 +482,7 @@ subroutine OverEnrichRegions(overenriching,mesh,NNew,Nmax,Nmin)
integer :: cornerID ! Corner counter
logical :: enriched(mesh % no_of_elements)
logical :: is_inside
integer :: i
!---------------------------------------

if (.not. allocated(overenriching) ) return
Expand Down
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