SMS:PTM Sediment File

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The PTM native sediment file contains the grain size information for the native sediments in terms of its D35, D50, and D90.

File Overview

The native sediments file contains the spatially-varying grain size information for the native sediments in terms of D35, D50 , and D90 . Frictional characteristics of the bed are computed with D90. The D50 value is used in the prediction of bed forms, in the determination of sediment mixing routines that influence reentrainment of deposited particles, and in the hiding and exposure routines that influence the critical shear stress of deposited particles. The D35 value is used in the determination of the suspended sediment transport if the van Rijn approach is selected for the centroid method. Non-erodible areas (e.g., rock outcroppings) can be identified by a negative input grain size. This absolute value of the grain size is treated as an effective roughness height, ks′ and ks′′.

The native sediments filename is specified on the Files page of the PTM model control. A native sediments file can be generated by the SMS interface, if one is required, by pressing the Create input file(s) from data... button on the Files tab of the PTM model control. This will open the Create PTM External Input Files dialog.

The native sediment file can be in ASCII or XMDF format.

ASCII File Overview

An ASCII format native sediment file is used when using an ADCIRC (fort.14 or *.grd), or CMS-Flow format mesh file (see PCF File keywords :MESH_FORMAT and :SEDIMENT_FORMAT).

  1. The first line is a comment line that is not read by PTM.
  2. The second line contains the number of elements and the number of nodes of the mesh.
  3. The next section contains a single line for each node, which gives the node number, easting (m), northing (m), D35 (mm), D50 (mm), and D90 (mm).
  4. The file extension should be specified as .sediments (for SMS)

Example ASCII Native Sediment Data File

      Node ID   X(m)      Y(m)      D35(mm)   D50(mm)   D90(mm)
      2704    1401
      1         54010.00  60160.00  0.13      0.19      0.3
      2         52008.90  60146.50  0.13      0.19      0.3
      3         50007.80  60133.00  0.13      0.19      0.3
      4         48006.70  60119.40  0.13      0.19      0.3
      5         46005.60  60105.90  0.13      0.19      0.3
      
      [Continued...]
      
      1397      -6825.58  -408.412  0.13      0.19      0.3
      1398      -6876.47  -481.815  0.13      0.19      0.3
      1399      -6950.30  -414.314  0.13      0.19      0.3
      1400      -6693.29  -533.139  0.13      0.19      0.3
      1401      -6793.13  -526.903  0.13      0.19      0.3

In this example, there are two information lines (one comment line and one line with the number of elements and number of nodes) followed by 1,401 lines of data. Each node has sediment with a D35 of 0.13 mm, D50 of 0.19 mm, and D90 of 0.3 mm.

XMDF File Overview

An XMDF format native sediment file is used when using an XMDF format mesh file (see keywords :MESH_FORMAT and :SEDIMENT_FORMAT).

  1. D35, D50, and D90 will be the same for every node when given as a property.
  2. D35, D50, and D90 can be spatially varied when given as a dataset.

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