Starting casu(>casu kanal 400) needs two arguments. i.) The first argument kanal is the name of the directory containing all files necessary to describe an individual case or model. casu looks for this directory at $CASU/test/kanal. Where $CASU is the shell-variable pointing to the directory casu is installed in. ii.)The second argument is the number of timesteps casu is going to compute. A case or model directory may contain files with the following names. 1 to 4 are needed to start casu, 5 is optional and 6 to 11 are files created by programs. casu expects m, kg and s as units of input-values. 1.) file.points contains the horizontal position of all mesh points i. e. nodes. The first line gives the number of nodes. The consecutive lines define the nodes. The first two figures in each line are the X- and Y-coordinates in meter of this node. The third and last number in the line is a boundary index telling which boundary line this boundary-node belongs to. Nodes that are no boundary-nodes have a 0 boundary index. See an example (test case kanal). 2.) file.elements describes the mesh connectivity. The first line gives the number of elements. The consecutive lines define the elements. The first number in each line is 3 or 4, telling whether this element has 3 or 4 corners. The following numbers are the nodenumbers of this element counter-clockwise. Numbering starts with 0, as usual in C-programs. Therefore you will find the horizontal coordinates of node #5 (for example) in the 7th line of file file.points. In the same way element #8 is found in the 10th line of file file.elements. See an example (test case kanal). 3.) file.control The control-file specifies all the parameters controlling the operation of the algorithm, like timestep, turbulence model, initial- and boundary-conditions of the flow field. file.control contains the vertical position of the levels (vertical discretization). A fully documented example from the "erosi" test case explains the lines of this file in detail. 4.) file_X.zone. The zone-file specifies the friction coefficient for each zone. Initial-and bottom-boundary-conditions for the turbulence quantities and the concentrations are defined in the zone-file(s) as well. The X in the name of the zone-file stands for the zone number. The area of a mesh may be subdivided into different zones. By default casu assumes 0 for the zone-number. An input-option, to assign zone-numbers to the elements, is not yet implemented. A fully documented example from the "erosi" test case explains the lines of this file in detail. 5.) file.ground assigns a bottom height to each node. If missing, a flat bottom at height 0 is assumed. See an example (test case kanal). 6.) rebin - At the end of each run, casu writes the values of all variables computed in the last timestep onto the binary file rebin. If a file named rebin exists when starting casu, a restart continuing from the timestep stored on rebin is performed. Ascii formatted output is generated by the auxiliary programs "check" and "out" that read the rebin file. 7.) logg - During runtime, information on the programs behaviour are logged on this file. 8.) W - If a lookat_node or a lookat_edge is given in the ##4## output control section of file.control, in each timestep the values for this node or edge are written onto a file named W. 9.) file.var is the output file of the auxiliary program "out" which can be read by mouse. 10.) plot is the output file of the auxiliary program "check". It contains the vertical distribution of values of the last node or edge displayed by "check". 11.) line.points contains the node numbers forming a line, that is used by the auxiliary program "sect" to create a vertical section. 12.) Anmerkungen (Ger. remarks) 13.) .mcl Files with the .mcl suffix control the operation of mouse. The auxiliary programs "check", "out", "sect", "fine" and "geneck" are part of the source.