Sediment Simulation - TriDiag FileSediment Simulation - TriDiag Filehttps://oss.deltares.nl/c/message_boards/find_thread?p_l_id=1806765&threadId=4012782021-01-26T06:48:48Z2021-01-26T06:48:48ZRE: Sediment Simulation - TriDiag FileAhmed Elkuthttps://oss.deltares.nl/c/message_boards/find_message?p_l_id=1806765&messageId=22440892019-03-26T09:14:34Z2019-03-26T09:14:34Z<p>Hi Richard</p> <p>Thanks a lot for your quick and resourceful reply.</p> <p>I was able, using the equation of NM, to estimate the location of the error. The problem seems to be located at the boundaries, and it covers few cells. </p> <p>I have only one sandy sediment fraction. I will try to reduce the timestep and check on the boundaries to fix this warning.</p> <p>Thanks again for your help.</p> <p> </p> <p>Ahmed</p>Ahmed Elkut2019-03-26T09:14:34ZRE: Sediment Simulation - TriDiag FileRichard Measureshttps://oss.deltares.nl/c/message_boards/find_message?p_l_id=1806765&messageId=22433662019-03-25T23:10:50Z2019-03-25T23:10:49Z<p>Hi Ahmed,</p> <p>A few thoughts in (partial) answer to your questions:</p> <p>1. The reference to NM 18538 I think refers to an internal model coordinate system where all cells are given a unique "nm" number. In the source code there is a function called "n_and_m_to_nm.f90" which uses the calculation "nm = n + nmaxddb * (m - 1 + ddb ) + ddb". ddb relates to domain decomposition so assuming you're not using multiple domains this simplifies to: NM = N + Nmax * (M-1). Using this equation you should be able to convert NM back to N & M based on Nmax.</p> <p>2. I have no idea!</p> <p>3. Do you have multiple sediment fractions? For multiple sediment fraction beds this warning relates to the amount of sediment available in the active (surface) layer, thus if there is insufficient sediment of a given fraction in the active layer you will get a warning even though there may be sediment available in the subsurface. Fixes can include reducing the timestep or increasing the thickness of the active layer.</p> <p>4. If the warning is only for 1 or two cells I would tend to ignore it. If it covers large areas of your domains for long periods of time then you probably need to fix it.</p> <p>Hope that helps.</p> <p>Richard</p>Richard Measures2019-03-25T23:10:49ZRE: Sediment Simulation - TriDiag FileAhmed Elkuthttps://oss.deltares.nl/c/message_boards/find_message?p_l_id=1806765&messageId=22423332019-03-25T11:20:45Z2019-03-25T11:20:45Z<p>Hi everyone</p> <p>I keep getting the same warning with initial sediment thickness of 5 meters, and I do not get it, I don't understand where is the erosion shortage occur for example if the error states: <strong>Sediment erosion shortage at NM 18538 Fraction: 1 Mass </strong> <strong>available :</strong> <strong> -0.138E-02 Mass to be eroded: -0.138E-02 </strong></p> <p> <strong>1. Where is that cell (NM 18538), does it mean (n,m)=(185,38) or (18,538)?, which is not either of them for me, or it is something else?</strong></p> <p> <strong>2. How can the mass available is exactly equal to the mass to be eroded?</strong></p> <p> <strong>3. How can I keep getting this error at the early stage of my simulation with maximum cum/erosion/sedimentation not exceeding 0.3m?</strong></p> <p> <strong>4. Does this error impact my simulation results, even though they qualitatively make sense?</strong></p> <p>I will appreciate any help</p> <p> <strong>Thanks</strong></p>Ahmed Elkut2019-03-25T11:20:45ZRE: Sediment Simulation - TriDiag FileQinghua Yehttps://oss.deltares.nl/c/message_boards/find_message?p_l_id=1806765&messageId=4045882014-03-26T14:39:53Z2014-03-26T14:39:53ZHi Patrick,<br /><br />I would not expect so as well. Did you observe big shear stress at the points as well? A bit strange and we need more info to analyze it.<br /><br />Regards,<br /><br />QinghuaQinghua Ye2014-03-26T14:39:53ZRE: Sediment Simulation - TriDiag FilePatrick Spechthttps://oss.deltares.nl/c/message_boards/find_message?p_l_id=1806765&messageId=4017652014-03-20T08:25:30Z2014-03-20T08:25:30ZDear Qinghua,<br /><br />thank you for your answer. <br /><br />I get this warnings right after starting the morphological changes and I have an initial sediment layer thickness of 25 m (uniform). That's why I wondered, why there should be no sediment left for erosion.<br /><br />Kind regards.<br />PatrickPatrick Specht2014-03-20T08:25:30ZRE: Sediment Simulation - TriDiag FileQinghua Yehttps://oss.deltares.nl/c/message_boards/find_message?p_l_id=1806765&messageId=4015122014-03-19T17:00:18Z2014-03-19T17:00:18ZDear Patrick,<br /><br />The message means in that cell, there is no sediment left for erosion at this timestep (bare bed, at least seem from the model ). There is possibility that this cell would get sedimentation as well. So it is not a problem, just a message for you to be aware of.<br /><br />Regards,<br /><br />QinghuaQinghua Ye2014-03-19T17:00:18ZSediment Simulation - TriDiag FilePatrick Spechthttps://oss.deltares.nl/c/message_boards/find_message?p_l_id=1806765&messageId=4012772014-03-19T10:59:35Z2014-03-19T10:59:30ZHallo everyone,<br /><br />within my actual sediment simulation I get follwoing lines in the tri-diag-files:<br /><br />Sediment erosion shortage at NM 6757 Fraction: 1 Mass available : -0.2684E-04 Mass to be eroded: -0.2684E-04<br /><br />What does that exactly mean and how can I avoid that problem?<br /><br />Many thanks and kind regards.<br />PatrickPatrick Specht2014-03-19T10:59:30Z