USER MANUAL SWAN Cycle III version 40.72A

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62 Chapter 4 | BSBT PROP < | Sec | | GSE [waveage] < MIn > | | HR | | | DAy | Command to choose: • the BSBT scheme (stationary and nonstationary) instead of the default S&L scheme (in case of nonstationary cases) or the default SORDUP scheme (in case of stationary cases) or • the wave age (for the default nonstationary S&L scheme). BSBT GSE [waveage] the BSBT scheme will be used in the computations. garden-sprinkler-effect is to be counteracted in the S&L propagation scheme (default for nonstationary computations) by adding a diffusion term to the basic equation. This may affect the numerical stability of SWAN (see Scientific/ Technical documentation). the time interval used to determine the diffusion which counteracts the so-called garden-sprinkler effect. The default value of [waveage] is zero, i.e. no added diffusion. The value of [waveage] should correspond to the travel time of the waves over the computational region. Notes: • All schemes (BSBT, SORDUP and S&L) can be used in combination with curvilinear grids. With the higher order schemes (S&L and SORDUP) it is important to use a gradually varying grid, otherwise there may be a severe loss of accuracy. If sharp transitions in the grid cannot be avoided it is safer to use the BSBT scheme. • In the computation with unstructured meshes, a first order upwind scheme will be employed. This scheme is very robust but rather diffusive. This may only be significant for the case when swell waves propagate over relative large distances (in the order of thousands of kilometers) within the model domain. | -> ACCUR [drel] [dhoval] [dtoval] [npnts] NUMeric ( < | STOPC [dabs] [drel] [curvat] [npnts] & | -> STAT [mxitst] [alfa] |
Description of commands 63 < > [limiter] ) & | NONSTAT [mxitns] | ( DIRimpl [cdd] [cdlim] ) & ( SIGIMpl [css] [eps2] [outp] [niter] ) & ( SETUP [eps2] [outp] [niter] ) With this optional command the user can influence some of the numerical properties of SWAN. ACCUR STOPC [dabs] With this option the user can influence the criterion for terminating the iterative procedure in the SWAN computations (both stationary and nonstationary mode). SWAN stops the iterations if: a) the change in the local significant wave height (H s ) from one iteration to the next is less than 1) fraction [drel] of that height or 2) fraction [dhoval] of the average significant wave height (average over all wet grid points) and b) the change in the local mean wave period (T m01 ) from one iteration to the next is less than 1) fraction [drel] of that period or 2) fraction [dtoval] of the average mean wave period (average over all wet grid points) and c) conditions a) and b) are fulfilled in more than fraction [npnts]% of all wet grid points. DEFAULT IN CASE OF STRUCTURED GRIDS. With this alternative option the user can influence the criterion for terminating the iterative procedure in the SWAN computations (both stationary and nonstationary). The criterion make use of the second derivative, or curvature, of the iteration curve of both the significant wave height and the mean period. As the solution of a simulation approaches full convergence, the curvature of the iteration curve will tend to zero. SWAN stops the process if the absolute change in both H s and T m01 from one iteration to the next is less than [dabs] or the relative change in H s and T m01 from one iteration to the next is less than [drel] and the curvature of the iteration curve of H s normalized with H s and that of T m01 normalized with T m01 is less than [curvat]. DEFAULT IN CASE OF UNSTRUCTURED GRIDS. Default: [dabs] = 0.00 [−] in case of structured grids; [dabs] = 0.005 [−] in case of unstructured grids.
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SWAN USER MANUAL SWAN Cycle III ver
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Contents 1 Introduction 1 2 General
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TABLE . . . . . . . . . . . . . . .
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Chapter 1 Introduction The informat
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Chapter 2 General definitions and r
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General definitions and remarks 5 r
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General definitions and remarks 7 I
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which SWAN performs the computation
Page 19 and 20: General definitions and remarks 11
Page 27 and 28: Chapter 3 Input and output files 3.
Page 29 and 30: Chapter 4 Description of commands 4
Page 31 and 32: (h) Commands to write or plot outpu
Page 33 and 34: Description of commands 25 ’name
Page 35 and 36: Description of commands 27 Default:
Page 37 and 38: Description of commands 29 mesh. Th
Page 39 and 40: ⎛ ∆f = ⎝−1 + Description of
Page 41 and 42: Description of commands 33 • Easy
Page 43 and 44: Description of commands 35 grids ca
Page 45 and 46: Description of commands 37 y ′
Page 47 and 48: Description of commands 39 [fac]
Page 49 and 50: Description of commands 41 ’(10X,
Page 51 and 52: Description of commands 43 | | East
Page 53 and 54: Description of commands 45 CONSTANT
Page 55 and 56: Description of commands 47 points o
Page 57 and 58: Description of commands 49 CRAY WKS
Page 59 and 60: Description of commands 51 This com
Page 61 and 62: Description of commands 53 | JANSse
Page 63 and 64: Description of commands 55 [Csh3] c
Page 65 and 66: Description of commands 57 [ursell]
Page 67 and 68: Description of commands 59 [slope]
Page 69: Description of commands 61 [cgmod]
Page 73 and 74: Description of commands 65 SIGIMPL
Page 75 and 76: Description of commands 67 ’sname
Page 77 and 78: Description of commands 69 (see bel
Page 79 and 80: Description of commands 71 [alpn] d
Page 81 and 82: Description of commands 73 ‘long
Page 83 and 84: | HSign | | | | HSWEll | | | | DIR
Page 85 and 86: Description of commands 77 | WLENgt
Page 87 and 88: Description of commands 79 QP DEPTH
Page 89 and 90: Description of commands 81 [tbegblk
Page 91 and 92: Description of commands 83 OUTput [
Page 93 and 94: Description of commands 85 If SWAN
Page 95 and 96: Description of commands 87 ACCUR MX
Page 97 and 98: Appendix A Definitions of variables
Page 99 and 100: Definitions of variables 91 RPER co
Page 101 and 102: Definitions of variables 93 WLEN Th
Page 103 and 104: Appendix B Command syntax B.1 Comma
Page 105 and 106: Repetitions of keywords and/or othe
Page 107 and 108: Required data and optional data Com
Page 109 and 110: Appendix C File swan.edt Below the
Page 111 and 112: File swan.edt 103 ! | -> DEFault !
Page 113 and 114: File swan.edt 105 ! FRAME ’sname
Page 115 and 116: Appendix D Spectrum files, input an
Page 117 and 118: 0.3892E-03 192.0 15.2 0.8007E-03 24
Page 119 and 120: Spectrum files, input and output 11
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Spectrum files, input and output 11
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Bibliography [1] SWAN - Implementat
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117 longitude, 8, 27, 49, 50, 85, 1
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USER MANUAL SWAN Cycle III version 40.72A

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