USER MANUAL SWAN Cycle III version 40.72A
USER MANUAL SWAN Cycle III version 40.72A USER MANUAL SWAN Cycle III version 40.72A
64 Chapter 4 [drel] [dhoval] [dtoval] [curvat] [npnts] STAT [mxitst] [alfa] NONSTAT [mxitns] [limiter] DIRIMPL [cdd] [cdlim] Default: [drel] = 0.02 [−] in case of ACCUR; [drel] = 0.01 [−] in case of STOPC. Default: [dhoval] = 0.02 [−] Default: [dtoval] = 0.02 [−] Default: [curvat] = 0.005 [−] Default: [npnts] = 98. [−] in case of structured grids; [npnts] = 99.5 [−] in case of unstructured grids. indicates the use of parameters in a stationary computation. the maximum number of iterations for stationary computations. The computation stops when this number is exceeded. Default: [mxitst] = 50. Note that [mxitst] can be set to 0 if one wants to check the input to the model without making computations. proportionality constant used in the frequency-dependent under-relaxation technique. Based on experiences, a suggestion for this parameter is [alfa] = 0.01. In case of diffraction computations, the use of this parameter is recommended. Default: [alfa] = 0.00. NOT MEANINGFUL FOR NONSTATIONARY COMPUTATIONS. indicates the use of parameters in a nonstationary computation. the maximum number of iterations per time step for nonstationary computations. The computation moves to the next time step when this number is exceeded. Default: [mxitns] = 1. Note that [mxitns] can be set to 0 if one wants to check the input to the model without making computations. determines, in both stationary and nonstationary runs, the maximum change per iteration of the energy density per spectral (σ,θ)-bin, given in terms of a fraction of the omni-directional Phillips level (see Scientific/ Technical documentation). Default: [limiter] = 0.1. this option is used to influence the numerical scheme for refraction. A value of [cdd]=0 corresponds to a central scheme and has the largest accuracy (diffusion ≈ 0) but the computation may more easily generate spurious fluctuations. A value of [cdd]=1. corresponds to an first order upwind scheme and it is more diffusive and therefore preferable if (strong) gradients in depth or current are present. Default: [cdd] = 0.5. If the spatial discretization of the bathymetry or the flow currents is too coarse, the waves may turn too far (more than 90 degrees, say) over one spatial grid step. The computational results will then be very inaccurate. In such a case SWAN can limit the maximum turning of the waves over one spatial grid to 90 degrees to obtain robust (but not necessarily correct results). [cdlim] < 0 then no limiter is used (this is default) [cdlim] = 0 refraction is off (same effect as command OFF REFRAC) [cdlim] = 4 waves turning limited to about 90 o over one spatial grid
Description of commands 65 SIGIMPL SETUP [css] [eps2] [outp] [niter] step. controls the accuracy of computing the frequency shifting and the stopping criterion and amount of output for the SIP solver (used in the computations in the presence of currents or time varying depth). controls the stopping criterion and amount of output for the SOR solver in the computation of the wave-induced set-up. A value of [css]=0 corresponds to a central scheme and has the largest accuracy (diffusion ≈ 0) but the computation may more easily generate spurious fluctuations. A value of [css]=1. corresponds to an first order upwind scheme and it is more diffusive and therefore preferable if (strong) gradients in depth or current are present. Default: [css] = 0.5. Relative stopping criterion to terminate the linear solver (SIP or SOR). The criterion for the SIP solver is based on ‖AN ⃗ k − ⃗ b‖ 2 ≤ [eps2] ‖ ⃗ b‖ 2 where A is a matrix, N ⃗ is the action density vector, ⃗ b is the right hand vector and k is the iteration number. The criterion for the SOR solver is based on ‖η k+1 − η k ‖ ∞ ≤ [eps2] where η is the set-up. Default: [eps2] = 1.e-4 in case of SIP and [eps2] = 1.e-6 in case of SOR. output for the iterative solver: 0 = no output 1 = additional information about the iteration process is written to the PRINT file 2 = gives a maximal amount of output concerning the iteration process 3 = summary of the iteration process Default: [outp] = 0. maximum number of iterations for the linear solver. Default: [niter] = 20 in case of SIP and [niter] = 1000 in case of SOR. 4.6 Output There are two categories of output commands: 1. Locations commands defining sets of output locations at which the user requires output. Each set is indicated with a name (’sname’ in this manual) which must be unique and not more than 8 characters long. Types of sets of output points: FRAME GROUP CURVE to define a set of output locations on a regular grid to define a set of output locations on a regular or curvi-linear grid to define a set of output locations along a curve
- Page 21 and 22: General definitions and remarks 13
- Page 23 and 24: General definitions and remarks 15
- Page 25 and 26: General definitions and remarks 17
- 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 and 70: Description of commands 61 [cgmod]
- Page 71: Description of commands 63 < > [lim
- 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
- Page 121 and 122: Spectrum files, input and output 11
64 Chapter 4<br />
[drel]<br />
[dhoval]<br />
[dtoval]<br />
[curvat]<br />
[npnts]<br />
STAT<br />
[mxitst]<br />
[alfa]<br />
NONSTAT<br />
[mxitns]<br />
[limiter]<br />
DIRIMPL<br />
[cdd]<br />
[cdlim]<br />
Default: [drel] = 0.02 [−] in case of ACCUR; [drel] = 0.01 [−] in case of STOPC.<br />
Default: [dhoval] = 0.02 [−]<br />
Default: [dtoval] = 0.02 [−]<br />
Default: [curvat] = 0.005 [−]<br />
Default: [npnts] = 98. [−] in case of structured grids; [npnts] = 99.5 [−]<br />
in case of unstructured grids.<br />
indicates the use of parameters in a stationary computation.<br />
the maximum number of iterations for stationary computations.<br />
The computation stops when this number is exceeded.<br />
Default: [mxitst] = 50.<br />
Note that [mxitst] can be set to 0 if one wants to check the input to the<br />
model without making computations.<br />
proportionality constant used in the frequency-dependent under-relaxation technique.<br />
Based on experiences, a suggestion for this parameter is [alfa] = 0.01.<br />
In case of diffraction computations, the use of this parameter is recommended.<br />
Default: [alfa] = 0.00.<br />
NOT MEANINGFUL FOR NONSTATIONARY COMPUTATIONS.<br />
indicates the use of parameters in a nonstationary computation.<br />
the maximum number of iterations per time step for nonstationary computations.<br />
The computation moves to the next time step when this number is exceeded.<br />
Default: [mxitns] = 1.<br />
Note that [mxitns] can be set to 0 if one wants to check the input to the<br />
model without making computations.<br />
determines, in both stationary and nonstationary runs, the maximum change per<br />
iteration of the energy density per spectral (σ,θ)-bin, given in<br />
terms of a fraction of the omni-directional Phillips level (see Scientific/<br />
Technical documentation).<br />
Default: [limiter] = 0.1.<br />
this option is used to influence the numerical scheme for refraction.<br />
A value of [cdd]=0 corresponds to a central scheme and has the largest<br />
accuracy (diffusion ≈ 0) but the computation may more easily generate<br />
spurious fluctuations. A value of [cdd]=1. corresponds to an first order<br />
upwind scheme and it is more diffusive and therefore preferable if (strong)<br />
gradients in depth or current are present.<br />
Default: [cdd] = 0.5.<br />
If the spatial discretization of the bathymetry or the flow currents is too coarse,<br />
the waves may turn too far (more than 90 degrees, say) over one spatial grid step.<br />
The computational results will then be very inaccurate. In such a case <strong>SWAN</strong> can<br />
limit the maximum turning of the waves over one spatial grid to 90 degrees to<br />
obtain robust (but not necessarily correct results).<br />
[cdlim] < 0 then no limiter is used (this is default)<br />
[cdlim] = 0 refraction is off (same effect as command OFF REFRAC)<br />
[cdlim] = 4 waves turning limited to about 90 o over one spatial grid
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