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Showing results for tags 'parameters'.
Hi ! I am relatively new to SMS and to AdH. I model a complex meandering river and overland flow situation. My model is 25 km long and combines parallel rivers in an extreme flood event (steady state). The floods cover the whole width of the valley (3.5 km) in many sections. I believe that I have been able to create a reasonable good mesh. I run a steady state simulation, I am into the first couple of hours of my calculation with these BC settings: IP MIT 200 IP NIT 1 IP NTL 0.01 IP ITL 0.01 TC STD 0.1 10.0 I allow for mesh refinement, for my riverbeds are really steep. This means that my mesh has quality issues of the “Maximum Slope” kind. Other issues I corrected, and I hope the mesh refinements by AdH will refine and handle these slope issues. I actually started with 290500 nodes, the model now runs with 320300 nodes. I set the IP NIT to 1, for I had issues with extreme and sudden time step reduction (factor 10000) during non-linear iteration steps. Setting the IP NIT to 1 solved this for the moment. AdH is calculating currently and will calculate for a while to come. I have basically identified three parameters to change in my BC file to make the calculation converge to the steady state solution. I will at one point have to reduce the NTL and ITL (AdH will state it has converged to a solution). I will at one point allow for non-linear iterations, moving to IP NIT 6 I can allow for bigger maximum time steps in the TD STD cardHow should I prioritize between these parameters? Will anyone help me by sharing his or her experiences? My dilemma is that If I allow for a bigger time step, my model might fail to converge, while if I decrease NTL and ITL, I do produce betters solutions, but that seems to be at the cost of calculation time. I imagine my most optimal calculation allows for big errors (say 0.01) and big time steps, for at the moment there is still a lot of water in my model that is not on the right location, not on the right water level, but I haven’t yet figured out how to set my calculation cards just for such a calculation. Especially towards the end of my calculations I am under the impression that I spend a lot on calculation time by reducing NTL and ITL, simply to keep AdH running. I need to reduce these cards, for AdH will state it has reached a valid solution when it errors stay within the set tolerance, but that does not mean it has reached the steady state solution. Anyone with ideas? Useful experiences you are willing to share? Thanks in advance!
I am running a transient PEST model with pilot points, using HK and RCH values. However, during the run I notice that the RCH values are not changing between optimization iterations. None of the points are defined as fixed. I created the RCH scatter points by duplicating the HK scatter points then editing the values. Could the additional "Active" field (populated with "1"'s) in the new RCH scatter point file be causing the problem? Both pilot-point-defined Parameters are referencing the correct scatter point sets. I am using 18 pilot points, but have over 100 Observation Points so I do not think I am violating that ratio. Thanks for your help! Chris