1
2!-----------------------------------------------------------------------
3      SUBROUTINE WAKE_SIG(X,XD,XOLD,TURBZ,TURBY,SZOLD,SYOLD,H,W,R,ZK,YK,&
4     &                    SZ,SY,DSZ)
5!-----------------------------------------------------------------------
6!
7! --- PRIME      Version:  1.0     Level:  970812              WAKE_SIG
8!                D. Strimaitis,   EARTH TECH
9!                Prepared for EPRI under contract WO3527-01
10!
11! --- PURPOSE: Calculates sigmas and d(sigma)/dx within the wake
12!              at a distance x from the upwind face of the bldg,
13!              prior to the ambient growth regime, for a "small"
14!              distance increment
15!
16! --- INPUTS:
17!                x - real        - dist (m) from upwind bldg face
18!               xd - real        - dist (m) at which PDF growth ends
19!             xold - real        - starting x of this step (m)
20!     turbz, turby - real        - current turbulence intensities
21!     szold, syold - real        - sigmas (m) at start of step
22!   htwake, hwwake - real        - height and half-width (m) of wake
23!           zk, yk - real        - matching constants for PDF transition
24!
25! --- OUTPUT:
26!
27!           zk, yk - real        - matching constants for PDF transition
28!           sz, sy - real        - sigmas (m) at end of step
29!              dsz - real        - d(sigmaz)/dx over step
30!
31! --- WAKE_SIG called by:  WAKE_DFSN
32! --- WAKE_SIG calls    :  WAKE_DIM
33!----------------------------------------------------------------------
34! --- Wake height from combination of Wilson (1979) and Weil (1996)
35! --- limits for uniform approach wind
36
37! --- Misc. constants
38      DATA TWO/2.0/
39
40! --- Get wake dimensions
41      CALL WAKE_DIM(X,H,W,R,HTWAKE,HWWAKE)                              !7144148
42
43! --- Use full width of the wake to scale lateral diffusivity
44      FWWAKE = TWO*HWWAKE
45
46      DELX = X - XOLD
47      XSTEPI = 1./DELX
48      IF ( X.LT.XD ) THEN
49! ---    Pure PDF Form
50         DSZ = TURBZ                                                    ! 820508
51         SZ = SZOLD + DELX*TURBZ
52         SY = SYOLD + DELX*TURBY
53      ELSEIF ( XOLD.GT.XD ) THEN
54! ---    Pure Wake Diffusivity Form
55         DSZ2 = ZK*TURBZ*HTWAKE                                         !6303836
56         DSY2 = YK*TURBY*FWWAKE
57         SZ = SQRT(SZOLD**2+DELX*DSZ2)
58         SY = SQRT(SYOLD**2+DELX*DSY2)
59         DSZ = (SZ-SZOLD)*XSTEPI
60      ELSE
61! ---    Transition from PDF to Diffusivity Form
62! ---    To end of PDF:
63         DELX = XD - XOLD                                               !  19804
64         SIGZD = SZOLD + DELX*TURBZ
65         SIGYD = SYOLD + DELX*TURBY
66         ZK = TWO*SIGZD/HTWAKE
67         YK = TWO*SIGYD/FWWAKE
68! ---    Beyond end of PDF:
69         DELX = X - XD
70         DSZ2 = ZK*TURBZ*HTWAKE
71         DSY2 = YK*TURBY*FWWAKE
72         SZ = SQRT(SIGZD**2+DELX*DSZ2)
73         SY = SQRT(SIGYD**2+DELX*DSY2)
74         DSZ = (SZ-SZOLD)*XSTEPI
75      ENDIF
76
77      CONTINUE                                                          !7144148
78      END


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