From 39a2165b7da5a431d3ba999983a180d33a5ee7d0 Mon Sep 17 00:00:00 2001
From: Roger Bergua <roger.bergua@nrel.gov>
Date: Thu, 24 Sep 2026 16:27:13 -0600
Subject: [PATCH 1/3] Only WrVTK=2 enforces final write

---
 modules/aerodyn/src/FVW.f90 | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/modules/aerodyn/src/FVW.f90 b/modules/aerodyn/src/FVW.f90
index 4df398a6d6..03447840e1 100644
--- a/modules/aerodyn/src/FVW.f90
+++ b/modules/aerodyn/src/FVW.f90
@@ -504,16 +504,11 @@ subroutine FVW_FinalWrite(u, p, x, z, OtherState, m, ErrStat, ErrMsg)
    ErrStat = ErrID_None
    ErrMsg  = ""
    ! Place any last minute operations or calculations here:
-   if (p%WrVTK>0 .and. m%VTKstep<FINAL_STEP .and. OtherState%Initialized) then
+   if (p%WrVTK==2 .and. m%VTKstep<FINAL_STEP .and. OtherState%Initialized) then
+      ! Only write final VTK outputs if WrVTK is set to 2
       call WrScr('OLAF: writing final VTK outputs')
       t=-1.0_ReKi
-      if (p%WrVTK==1) then
-         if (m%VTKstep<m%iStep+1) then
-            call WriteVTKOutputs(t, .true., m%iStep+1, u, p, x, z, m, ErrStat, ErrMsg)
-         endif
-      elseif (p%WrVTK==2) then
-         call WriteVTKOutputs(t, .true., FINAL_STEP, u, p, x, z, m, ErrStat, ErrMsg)
-      endif
+      call WriteVTKOutputs(t, .true., FINAL_STEP, u, p, x, z, m, ErrStat, ErrMsg)
       m%VTKstep = FINAL_STEP ! We make sure we don't write again
    endif
 end subroutine FVW_FinalWrite

From ea3b1084f40d9252a1e5c8f981ad162bd5a20f82 Mon Sep 17 00:00:00 2001
From: Roger Bergua <roger.bergua@nrel.gov>
Date: Thu, 24 Sep 2026 16:30:06 -0600
Subject: [PATCH 2/3] Decouple grid outputs from WrVTK

---
 modules/aerodyn/src/FVW.f90 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/modules/aerodyn/src/FVW.f90 b/modules/aerodyn/src/FVW.f90
index 03447840e1..e4a97c86d2 100644
--- a/modules/aerodyn/src/FVW.f90
+++ b/modules/aerodyn/src/FVW.f90
@@ -1612,7 +1612,7 @@ subroutine WriteVTKOutputs(t, force, VTKstep, u, p, x, z, m, ErrStat, ErrMsg)
       do iGrid=1,p%nGridOut
          bWithinTime   = t>=m%GridOutputs(iGrid)%tStart-p%DTaero/2. .and. t<= m%GridOutputs(iGrid)%tEnd+p%DTaero/2.
          bTimeToOutput = ( t - m%GridOutputs(iGrid)%tLastOutput) >= m%GridOutputs(iGrid)%DTout - 0.25_DbKi*p%DTaero
-         bDoGrid(iGrid) = force .or. (bWithinTime .and. bTimeToOutput)
+         bDoGrid(iGrid) = bWithinTime .and. bTimeToOutput
       enddo
       if (any(bDoGrid)) then
          ! Build the wake segments/tree once and reuse it for all grids below

From 0873538dbc5cfb22b50a29f2f7b3eccb91040331 Mon Sep 17 00:00:00 2001
From: Roger Bergua <roger.bergua@nrel.gov>
Date: Fri, 25 Sep 2026 11:47:27 -0600
Subject: [PATCH 3/3] OLAF: fix missing VTK output at final time step for
 WrVTK=1

---
 modules/aerodyn/src/FVW.f90 | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/modules/aerodyn/src/FVW.f90 b/modules/aerodyn/src/FVW.f90
index e4a97c86d2..59d0292555 100644
--- a/modules/aerodyn/src/FVW.f90
+++ b/modules/aerodyn/src/FVW.f90
@@ -504,11 +504,18 @@ subroutine FVW_FinalWrite(u, p, x, z, OtherState, m, ErrStat, ErrMsg)
    ErrStat = ErrID_None
    ErrMsg  = ""
    ! Place any last minute operations or calculations here:
-   if (p%WrVTK==2 .and. m%VTKstep<FINAL_STEP .and. OtherState%Initialized) then
-      ! Only write final VTK outputs if WrVTK is set to 2
-      call WrScr('OLAF: writing final VTK outputs')
-      t=-1.0_ReKi
-      call WriteVTKOutputs(t, .true., FINAL_STEP, u, p, x, z, m, ErrStat, ErrMsg)
+   ! NOTE: the driver's main loop calls CalcOutput one step behind UpdateStates, so the very last
+   !       simulated state is never seen by CalcOutput. Force it here if it wasn't written yet.
+   if (p%WrVTK>0 .and. m%VTKstep<FINAL_STEP .and. OtherState%Initialized) then
+      t = real(m%iStep+1, DbKi) * p%DTaero
+      if (p%WrVTK==2) then
+         ! WrVTK=2 guarantees a wake output at the end of the simulation, regardless of VTK_fps
+         call WrScr('OLAF: writing final VTK outputs')
+         call WriteVTKOutputs(t, .true., FINAL_STEP, u, p, x, z, m, ErrStat, ErrMsg)
+      elseif (m%VTKstep<m%iStep+1 .and. (t - m%VTKlastTime) >= p%DTvtk - 0.25_DbKi*p%DTaero) then
+         ! WrVTK=1: only write the final step if it wasn't caught yet and it lines up with VTK_fps
+         call WriteVTKOutputs(t, .true., m%iStep+1, u, p, x, z, m, ErrStat, ErrMsg)
+      endif
       m%VTKstep = FINAL_STEP ! We make sure we don't write again
    endif
 end subroutine FVW_FinalWrite