FDS Source: Issue #13696. Clarify use of INITIAL_SPEED

Manuals/FDS_User_Guide/FDS_User_Guide.tex

@@ -6844,7 +6844,7 @@ \subsection{Pressure Gradient Force}
 &RAMP ID='dir', T= 600, F=330 /
 &RAMP ID='dir', T=1200, F=350 /
 \end{lstlisting}
-Here, {\ct T} is time in seconds and {\ct F} is the wind direction in degrees. The {\ct INITIAL\_SPEED} sets the horizontal wind components at the start of the simulation. This is provided as a convenience because it may take on the order of hours of simulation time to slowly increase the wind speed via the pressure gradient force alone. The {\ct INITIAL\_SPEED} only sets the initial wind speed, but has no longer term effect. You may vary the {\ct PRESSURE\_GRADIENT\_FORCE} in time using {\ct RAMP\_PGF\_T}.
+Here, {\ct T} is time in seconds and {\ct F} is the wind direction in degrees. The {\ct INITIAL\_SPEED} and {\ct INITIAL\_DIRECTION} set the horizontal wind components at the start of the simulation. This is provided as a convenience because it may take on the order of hours of simulation time to slowly increase the wind speed via the pressure gradient force alone. The {\ct INITIAL\_SPEED} {\ct INITIAL\_DIRECTION} only set the initial wind speed and direction, but has no longer term effect. You may vary the {\ct PRESSURE\_GRADIENT\_FORCE} in time using {\ct RAMP\_PGF\_T}.
 
 There are some applications, like tunnels, where the pressure gradient force is a convenient way to introduce an air flow due to some external force. In such cases, it is sometimes more convenient to use the vector {\ct FORCE\_VECTOR(1:3)} along with the corresponding time ramps {\ct RAMP\_FVX\_T}, {\ct RAMP\_FVY\_T}, and {\ct RAMP\_FVZ\_T} to control each individual component. The {\ct PRESSURE\_GRADIENT\_FORCE} is simply the magnitude of the {\ct FORCE\_VECTOR} with the same units.
 
@@ -13673,6 +13673,7 @@ \section{\texorpdfstring{{\tt WIND}}{WIND} (Wind and Atmospheric Parameters)}
 {\ct FORCE\_VECTOR(3)}                          & Real          & Section~\ref{info:force_vector}               & Pa/m          & 0.                \\ \hline
 {\ct GEOSTROPHIC\_WIND(2)}                      & Real          & Section~\ref{info:geostrophic_wind}           & m/s           &                   \\ \hline
 {\ct GROUND\_LEVEL}                             & Real          & Section~\ref{info:stratification}             & m             & 0.                \\ \hline
+{\ct INITIAL\_DIRECTION}                        & Real          & Section~\ref{info:force_vector}               & deg           & 270.              \\ \hline
 {\ct INITIAL\_SPEED}                            & Real          & Section~\ref{info:force_vector}               & m/s           & 0.                \\ \hline
 {\ct L}                                         & Real          & Section~\ref{info:WIND}                       & m             & 0                 \\ \hline
 {\ct LAPSE\_RATE}                               & Real          & Section~\ref{info:stratification}             & $^\circ$C/m   & 0                 \\ \hline

Source/ccib.f90

@@ -2208,11 +2208,7 @@ SUBROUTINE GET_PRES_CFACE_BCS(NM,T,DT)
 
          ! Wind inflow boundary conditions
 
-         IF (INITIAL_SPEED>0._EB) THEN
-            H0 = 0._EB
-         ELSE
-            H0 = 0.5_EB*(U0**2+V0**2+W0**2)
-         ENDIF
+         H0 = 0.5_EB*(U0**2+V0**2+W0**2)
          IF (OPEN_WIND_BOUNDARY) &
          H0 = 0.5_EB*((U_WIND(K)+VEL_EDDY)**2 + (V_WIND(K)+VEL_EDDY)**2 + (W_WIND(K)+VEL_EDDY)**2)
 

Source/cons.f90

@@ -309,6 +309,7 @@ MODULE GLOBAL_CONSTANTS
 REAL(EB) :: V0                                 !< Wind speed in the \f$ y \f$ direction (m/s)
 REAL(EB) :: W0                                 !< Wind speed in the \f$ z \f$ direction (m/s)
 REAL(EB) :: INITIAL_SPEED=-1._EB               !< Initial wind speed (m/s) which is assumed to die off
+REAL(EB) :: INITIAL_DIRECTION=270._EB          !< Initial wind direction (deg)
 REAL(EB) :: GVEC(3)                            !< Gravity vector (m/s2)
 REAL(EB) :: FVEC(3)=0._EB                      !< Force vector (N/m3)
 REAL(EB) :: OVEC(3)=0._EB                      !< Coriolis vector (1/s)

Source/init.f90

@@ -360,14 +360,23 @@ SUBROUTINE INITIALIZE_MESH_VARIABLES_1(DT,NM)
 CALL COMPUTE_WIND_COMPONENTS(T_BEGIN,NM)
 
 DO K=0,M%KBP1
-   M%RHO(:,:,K) = M%RHO_0(K)
-   M%RHOS(:,:,K)= M%RHO_0(K)
-   M%TMP(:,:,K) = M%TMP_0(K)
-   M%U(:,:,K)   = M%U_WIND(K)
-   M%V(:,:,K)   = M%V_WIND(K)
-   M%W(:,:,K)   = M%W_WIND(K)
+   M%RHO(:,:,K)  = M%RHO_0(K)
+   M%RHOS(:,:,K) = M%RHO_0(K)
+   M%TMP(:,:,K)  = M%TMP_0(K)
 ENDDO
 
+IF (INITIAL_SPEED<0._EB) THEN
+   DO K=0,M%KBP1
+      M%U(:,:,K) = M%U_WIND(K)
+      M%V(:,:,K) = M%V_WIND(K)
+      M%W(:,:,K) = M%W_WIND(K)
+   ENDDO
+ELSE
+   M%U = -INITIAL_SPEED*SIN(INITIAL_DIRECTION*DEG2RAD)
+   M%V = -INITIAL_SPEED*COS(INITIAL_DIRECTION*DEG2RAD)
+   M%W = 0._EB
+ENDIF
+
 ! Custom velocity RAMPS (for verification)
 
 IF (I_RAMP_UX>0) THEN
@@ -425,13 +434,8 @@ SUBROUTINE INITIALIZE_MESH_VARIABLES_1(DT,NM)
 M%FVY   = 0._EB
 M%FVZ   = 0._EB
 M%KRES  = 0._EB
-IF (INITIAL_SPEED>0._EB) THEN
-   M%H  = 0._EB
-   M%HS = 0._EB
-ELSE
-   M%H  = 0.5_EB*(U0**2+V0**2+W0**2)
-   M%HS = 0.5_EB*(U0**2+V0**2+W0**2)
-ENDIF
+M%H     = 0.5_EB*(U0**2+V0**2+W0**2)
+M%HS    = 0.5_EB*(U0**2+V0**2+W0**2)
 M%DDDT  = 0._EB
 M%D     = 0._EB
 M%DS    = 0._EB

Source/pres.f90

@@ -170,11 +170,7 @@ SUBROUTINE PRESSURE_SOLVER_COMPUTE_RHS(T,DT,NM)
 
          ! Wind inflow boundary conditions
 
-         IF (INITIAL_SPEED>0._EB) THEN
-            H0 = 0._EB
-         ELSE
-            H0 = 0.5_EB*(U0**2+V0**2+W0**2)
-         ENDIF
+         H0 = 0.5_EB*(U0**2+V0**2+W0**2)
 
          IF (OPEN_WIND_BOUNDARY) THEN
             SELECT CASE(IOR)

Source/read.f90

@@ -2077,8 +2077,8 @@ SUBROUTINE READ_WIND
 TYPE(RESERVED_RAMPS_TYPE), POINTER :: RRP,RRPX
 INTEGER, PARAMETER :: N_MO_PTS=51 ! number of Monin-Obukhov ramp points
 
-NAMELIST /WIND/ CORIOLIS_VECTOR,DIRECTION,FORCE_VECTOR,FYI,GEOSTROPHIC_WIND,GROUND_LEVEL,INITIAL_SPEED,L,LAPSE_RATE,LATITUDE,&
-                PRESSURE_GRADIENT_FORCE,RAMP_DIRECTION_T,RAMP_DIRECTION_Z,&
+NAMELIST /WIND/ CORIOLIS_VECTOR,DIRECTION,FORCE_VECTOR,FYI,GEOSTROPHIC_WIND,GROUND_LEVEL,INITIAL_DIRECTION,INITIAL_SPEED,&
+                L,LAPSE_RATE,LATITUDE,PRESSURE_GRADIENT_FORCE,RAMP_DIRECTION_T,RAMP_DIRECTION_Z,&
                 RAMP_PGF_T,RAMP_FVX_T,RAMP_FVY_T,RAMP_FVZ_T,RAMP_SPEED_T,RAMP_SPEED_Z,RAMP_TMP0_Z,&
                 SIGMA_THETA,SPEED,STRATIFICATION,TAU_THETA,THETA_STAR,TMP_REF,U_STAR,U0,&
                 USE_ATMOSPHERIC_INTERPOLATION,V0,W0,Z_0,Z_REF
@@ -2142,14 +2142,14 @@ SUBROUTINE READ_WIND
    SPEED = (U_STAR/VON_KARMAN_CONSTANT)*(LOG(Z_REF/Z_0)-PSI_M)
 ENDIF
 
-IF (SPEED>0._EB .OR. INITIAL_SPEED>0._EB) THEN
+IF (SPEED>0._EB) THEN
    IF (SPEED>0._EB) OPEN_WIND_BOUNDARY = .TRUE.
    IF (RAMP_DIRECTION_T/='null' .OR. RAMP_DIRECTION_Z/='null') THEN
-      U0 = MAX(SPEED,INITIAL_SPEED)
-      V0 = MAX(SPEED,INITIAL_SPEED)
+      U0 = SPEED
+      V0 = SPEED
    ELSE
-      U0 = -MAX(SPEED,INITIAL_SPEED)*SIN(DIRECTION*DEG2RAD)
-      V0 = -MAX(SPEED,INITIAL_SPEED)*COS(DIRECTION*DEG2RAD)
+      U0 = -SPEED*SIN(DIRECTION*DEG2RAD)
+      V0 = -SPEED*COS(DIRECTION*DEG2RAD)
    ENDIF
 ENDIF
 

Validation/Askervein_Hill/FDS_Input_Files/Askervein_TU03A_16m.fds

@@ -20,7 +20,7 @@
 &RADI RADIATION=F /
 
 ! See Ask83 Table 4.7
-&WIND INITIAL_SPEED=10.0, DIRECTION=206, L=-691., Z_0=0.08, Z_REF=10., GROUND_LEVEL=0 /
+&WIND SPEED=10.0, DIRECTION=206, L=-691., Z_0=0.08, Z_REF=10., GROUND_LEVEL=0 /
 
 ! External BCs:
 &VENT MB='XMIN',SURF_ID='OPEN'/

Validation/Loughborough_Jet_Fires/FDS_Input_Files/jet1.fds

@@ -14,7 +14,7 @@
 &VENT MB='XMIN', SURF_ID='OPEN' /
 &VENT MB='XMAX', SURF_ID='OPEN' /
 
-&WIND INITIAL_SPEED=6.3, DIRECTION=271., PRESSURE_GRADIENT_FORCE=0.08 /
+&WIND INITIAL_SPEED=6.3, INITIAL_DIRECTION=271., DIRECTION=271., PRESSURE_GRADIENT_FORCE=0.08 /
 
 &SURF ID='GROUND', ROUGHNESS=0.5 /
 

Validation/Loughborough_Jet_Fires/FDS_Input_Files/jet2.fds

@@ -14,7 +14,7 @@
 &VENT MB='XMIN', SURF_ID='OPEN' /
 &VENT MB='XMAX', SURF_ID='OPEN' /
 
-&WIND INITIAL_SPEED=6.2, DIRECTION=297., PRESSURE_GRADIENT_FORCE=0.08 /
+&WIND INITIAL_SPEED=6.2, INITIAL_DIRECTION=297., DIRECTION=297., PRESSURE_GRADIENT_FORCE=0.08 /
 
 &SURF ID='GROUND', ROUGHNESS=0.5 /
 

Validation/Loughborough_Jet_Fires/FDS_Input_Files/jet3.fds

@@ -14,7 +14,7 @@
 &VENT MB='XMIN', SURF_ID='OPEN' /
 &VENT MB='XMAX', SURF_ID='OPEN' /
 
-&WIND INITIAL_SPEED=3.6, DIRECTION=267., PRESSURE_GRADIENT_FORCE=0.08 /
+&WIND INITIAL_SPEED=3.6, INITIAL_DIRECTION=267., DIRECTION=267., PRESSURE_GRADIENT_FORCE=0.08 /
 
 &SURF ID='GROUND', ROUGHNESS=0.5 /
 

Verification/Atmospheric_Effects/lee_waves.fds

@@ -7,10 +7,8 @@ It is a two-dimensional calculation of wind flow over a mountain range.
 
 &TIME T_END=6000.0 / 
 
-&WIND U0=5.0,LAPSE_RATE=0.005 /
-&RADI RADIATION=.FALSE./
-&SURF ID='WIND',VEL=-5.0,PROFILE='ATMOSPHERIC',PLE=0. /
-&SURF ID='SLIP',FREE_SLIP=.TRUE. /
+&WIND SPEED=5.0, LAPSE_RATE=0.005 /
+&RADI RADIATION=F /
 
 &OBST XB=2000.0,3000.0,-1.0,1.0,  0.0,100.0/
 &OBST XB=2100.0,2900.0,-1.0,1.0,100.0,200.0/
@@ -26,8 +24,8 @@ It is a two-dimensional calculation of wind flow over a mountain range.
 &SLCF PBY=0.0, QUANTITY='VELOCITY', VECTOR=.TRUE. /
 
 &VENT MB='XMAX' ,SURF_ID='OPEN' /
-&VENT MB='XMIN', SURF_ID='WIND' /
-&VENT MB='ZMAX' ,SURF_ID='SLIP' /
+&VENT MB='XMIN', SURF_ID='OPEN' /
+&VENT MB='ZMAX' ,SURF_ID='OPEN' /
 
 &TAIL /
 

Verification/Complex_Geometry/geom_stretched_grid.fds

@@ -13,7 +13,7 @@
 
 &GEOM XB=-1200,-800,-1600,-1200,400,800/ GEOM on stretch mesh
 
-&WIND INITIAL_SPEED=10.0, DIRECTION=206 /
+&WIND SPEED=10.0, DIRECTION=206 /
 
 ! External BCs:
 &VENT MB='XMIN',SURF_ID='OPEN'/