HVAC subroutine

[Er9y714]

Hi,

I am trying to understand the difference between Pressure Zone Leakage and Localized leakage.
What I follow through:

DU%LEAKAGE and DU%LOCALIZED_LEAKAGE represent them, respectively.

DU%AREA is adjusted in SUBROUTINE ADJUST_LEAKAGE_AREA and SUBROUTINE DETERMINE_FIXED_ELEMENTS(T, CHANGE)

In SUBROUTINE DETERMINE_FIXED_ELEMENTS FDS resets the area of dynamic leaks to their physical value at the beginning of each timestep. But only DU%LEAKAGE is checked. Why is DU%LOCALIZED_LEAKAGE not checked here?

Thank you.

SUBROUTINE DETERMINE_FIXED_ELEMENTS(T, CHANGE)
...
DUCT_LOOP: DO ND=1,N_DUCTS
   DU=>DUCT(ND)
   ...
   ! If leakage and no vent area then set duct area to zero
   IF (DU%LEAKAGE) THEN
      ZERO_AREA = .FALSE.
      ...
      IF (ZERO_AREA) THEN
         DU%AREA = 0._EB
         DU%VEL  = 0._EB
      ELSE
         DU%AREA = DU%AREA_INITIAL
      ENDIF
   ENDIF

fds/Source/hvac.f90

Lines 2563 to 2586 in 42aadc9

	! If leakage and no vent area then set duct area to zero
	IF (DU%LEAKAGE) THEN
	ZERO_AREA = .FALSE.
	IF (ALLOCATED(CONNECTED_ZONES)) THEN
	IF (DUCTNODE(DU%NODE_INDEX(1))%ZONE_INDEX>0 .AND. DUCTNODE(DU%NODE_INDEX(2))%ZONE_INDEX>0) THEN
	IF (CONNECTED_ZONES(0,DUCTNODE(DU%NODE_INDEX(1))%ZONE_INDEX)==1 .AND. &
	CONNECTED_ZONES(0,DUCTNODE(DU%NODE_INDEX(2))%ZONE_INDEX)==1) ZERO_AREA = .TRUE.
	ELSEIF (DUCTNODE(DU%NODE_INDEX(1))%ZONE_INDEX>0 .AND. DUCTNODE(DU%NODE_INDEX(2))%ZONE_INDEX<=0) THEN
	IF (CONNECTED_ZONES(0,DUCTNODE(DU%NODE_INDEX(1))%ZONE_INDEX)==1) ZERO_AREA = .TRUE.
	ELSEIF (DUCTNODE(DU%NODE_INDEX(1))%ZONE_INDEX<=0 .AND. DUCTNODE(DU%NODE_INDEX(2))%ZONE_INDEX>0) THEN
	IF (CONNECTED_ZONES(0,DUCTNODE(DU%NODE_INDEX(2))%ZONE_INDEX)==1) ZERO_AREA = .TRUE.
	ENDIF
	ENDIF
	IF (NODE_AREA_EX(DU%NODE_INDEX(1)) < TWENTY_EPSILON_EB .AND. .NOT. DUCTNODE(DU%NODE_INDEX(1))%AMBIENT) &
	ZERO_AREA=.TRUE.
	IF(NODE_AREA_EX(DU%NODE_INDEX(2)) < TWENTY_EPSILON_EB .AND. .NOT. DUCTNODE(DU%NODE_INDEX(2))%AMBIENT) &
	ZERO_AREA=.TRUE.
	IF (ZERO_AREA) THEN
	DU%AREA = 0._EB
	DU%VEL = 0._EB
	ELSE
	DU%AREA = DU%AREA_INITIAL
	ENDIF
	ENDIF

[drjfloyd]

Pressure zone leakage uses only the zone pressure. It has no VENTs associated with it. Localized leakage uses the pressure outside the pair of VENTs associated with the leakage path. The different approaches require different handling in terms of defining if there is an available flowpath.

[Er9y714]

Thank you,