Search the Community
Showing results for tags 'adh'.
Found 3 results
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've been using WMS for several years but I am new user of SMS, specifically, the AdH program implementation. Recalling that the learning curve is pretty substantial from my experience with WMS, I've gone through a similar self-taught process of going through the SMS and AdH User Manuals, Learning Center tutorials, video and SMS Wiki. I did follow the AdH Intro tutorial and successfully setup the model and executed it. However, after 1 hour of simulation time (out of the 36 hour) and a run-time of 3 hours, I aborted. The tutorial indicates that depending on the speed of your computer, the model will finish in 1 - 2 hours. My laptop is a Dell Latitude, 16 GB RAM, Intel Core i7 processor with plenty of disk space. Is this a hardware limitation or an issue of computational settings (which I left to default just like the tutorial)? The above resources helped me setup my model. I imported a AutoCAD .dwg file and created scatter points from the contours & created a mesh, which turned out to be extremely dense due to the excessive vertex points SMS generated as a result of the AutoCAD contour vertices. So as an alternative, I manually defined scatter points along known elevations/contours at a less refined spacing. I generated a mesh which looked much better in terms of shapes and density. I was able to define the materials designated on the basis of channel, overbanks, and paved surfaces and correspondingly defined the boundaries based on these designated areas. I created nodestrings to define the upstream and downstream boundary conditions as Total Discharge and Water Surface Elevations, respectively, that varied for a 6 hour simulation. I created the AdH Hot Start (depth/elevation). When I ran the AdH Model Check, it gives me the triangle bad aspect error (17 in all). Following the recommendation, I went back to change the aspect ratio from the default 0.04 to 0.1 and regenerated the mesh, which gave me even more bad aspect triangles. I couldn't manually merge triangles or convert them to quadralaterals. Is option available for AdH models? I've been spinning my wheels for the past couple of weeks, so I am officially stuck and in need of some guidance from experienced users and/or developers. Sorry for the verbosity & appreciate any constructive feedback, Tamim