Concentration in FLOW: Pollutants and tracersConcentration in FLOW: Pollutants and tracershttps://oss.deltares.nl/c/message_boards/find_thread?p_l_id=1806765&threadId=7274532020-12-02T16:17:09Z2020-12-02T16:17:09ZRE: Concentration in FLOW: Pollutants and tracersReed Jonashttps://oss.deltares.nl/c/message_boards/find_message?p_l_id=1806765&messageId=31714802020-08-01T10:20:16Z2020-08-01T10:20:16ZNice, thanks for sharing this information <a href="https://tellthebell.onl/">tellthebell</a>.Reed Jonas2020-08-01T10:20:16ZRE: Concentration in FLOW: Pollutants and tracersKaroline Lilliehttps://oss.deltares.nl/c/message_boards/find_message?p_l_id=1806765&messageId=31619512020-07-29T08:58:34Z2020-07-29T08:58:34ZHello everyone,<br />I have a very similar question and would like to verify if I understand the "unit" of the tracer correctly. I am working with the Flexible Mesh, but I assume this is still handled the same way:<br />I have a flow model with no temperature, no sediment, just tracer. I defined a source with a constant discharge (0.5 m3/s) and a constant "concentration" for the tracer of 100 (the GUI shows kg/m3 as unit).<br />When I extract the model results for my tracer with matlab/quickplot the unit is empty "". And following the response from Bert Jagers that is because there is no unit attached to the tracer.<br />The question is: If i go in with 100 for my tracer, could I regard the results as Percent of the input concentration and substitute with any volumetric concentration? Lets say a particular cell gives me the result of 0.5 for the tracer, is that then 0.5% of my original 100 tracer? And hence if I assume i go in with 100 mg/l that means I will have 0.5mg/l in that particular cell? I do believe, that is how it works but I would like to be sure.<br />I hope this makes sense...Karoline Lillie2020-07-29T08:58:34ZRE: Concentration in FLOW: Pollutants and tracersMichael O'Sheahttps://oss.deltares.nl/c/message_boards/find_message?p_l_id=1806765&messageId=14297452018-01-17T11:10:06Z2018-01-16T14:12:10ZThanks Bert,<br /><br />See attached screen shots. I have a sediment (Sediment 2) and a pollutant (dredge material) specified as discharges.<br />They both have units of kg/m3 as default inputs. I want to simulate the effect of plough dredging by discharging sediment in one grid cell over an 8 hour period.<br />I believe the sediment fraction is the correct approach. My figures show 2600 kg/m3 of sediment2 released at a rate of 0.02 m3/s. Am I correct in saying this equates to a total discharge of 576m3/ day (8hours)?Michael O'Shea2018-01-16T14:12:10ZRE: Concentration in FLOW: Pollutants and tracersBert Jagershttps://oss.deltares.nl/c/message_boards/find_message?p_l_id=1806765&messageId=14123482017-12-21T17:34:34Z2017-12-21T17:34:34ZHi Michael,<br /><br />What quantity are you looking at: the <em>concentration</em> of the plough dredged sediment on the trim-file?<br />Do you model the sediment in Delft3D as a sediment fraction or as a pollutant/tracer?<br />In the former case (sediment fraction) QUICKPLOT should indicate the unit kg/m^3 .... which version of QUICKPLOT are you using?<br />In the latter case (pollutant/tracer) QUICKPLOT doesn't know what unit quantity is specified in because Delft3D never asks you for the unit - you can use any volumetric concentration (m3/m3, kg/m3, mg/m3).<br /><br />Best regards,<br /><br />BertBert Jagers2017-12-21T17:34:34ZRE: Concentration in FLOW: Pollutants and tracersMichael O'Sheahttps://oss.deltares.nl/c/message_boards/find_message?p_l_id=1806765&messageId=14112482017-12-20T13:50:00Z2017-12-20T13:50:00ZHi Adri,<br /><br />I have a similar issue, <br /><br />I have specified a discharge in one cell only with low velocity 0.01 m3/s and concentration of 1800 kg/m3 over a time period within a Delft Flow simulation. The purpose is to simulate plough dredge sediment release.<br /><br />When I view the results in Quickplot for a plan view of the discharge I am unsure of the units being displayed for the spread of the discharge.<br /><br />What units are the default? it appears to be Kg/m3 but its not clear?Michael O'Shea2017-12-20T13:50:00ZRE: Concentration in FLOW: Pollutants and tracersMiguel Reyeshttps://oss.deltares.nl/c/message_boards/find_message?p_l_id=1806765&messageId=7461662015-10-13T08:33:43Z2015-10-13T08:33:43ZThanks a lot, Adri, it solved my problems!Miguel Reyes2015-10-13T08:33:43ZRE: Concentration in FLOW: Pollutants and tracersAdri Mouritshttps://oss.deltares.nl/c/message_boards/find_message?p_l_id=1806765&messageId=7431592015-10-08T10:19:26Z2015-10-08T10:19:26ZHi Miguel,<br /><br />1) In pseudo code:<br /><div class="lfr-code"><table><tbody><tr><td class="line-numbers" data-line-number="1"></td><td class="lines"><div class="line">"c1-trih" = ("Q1" * "c1" + "volume_cell" * "c0-trih") / ("Q1" + "volume_cell")</div></td></tr></tbody></table></div><br />with "volume_cell" = volume of the cell at the old time step, "c0-trih" = the concentration in the cell at the old time step<br /><br />The reference time (=reference date, 00:00:00 hours) in the discharge file must be the same as in the mdf file. The GUI should help you with this.<br /><br />2) Yes. When using an ini file you prescribe "c0-trih".<br /><br />Regards,<br /><br />AdriAdri Mourits2015-10-08T10:19:26ZConcentration in FLOW: Pollutants and tracersMiguel Reyeshttps://oss.deltares.nl/c/message_boards/find_message?p_l_id=1806765&messageId=7274522015-09-15T14:29:48Z2015-09-15T14:29:37ZHi everyone:<br />I have a problem when assessing the results of Pollutants and tracers.<br /> <br />At a certain moment "t1", I define a discharge (normal, block interpolation) in one (M,N) location (Flow rate " Q1" and Tracer concentration "c1"). In the next time "t2" ("t1"+history interval), the value of the discharge is null. When I open the trih file in this observation point, the initial concentration "c1-trih" does not correspond to the defined value in the discharge "c1". I mean, I played with the concentration, flow rate and grid cell volume of the discharge; but I found no relation between "c1" and "c1-trih". What I could see is that a linear increase in the discharge (2*Q1) implies a linear increase in this concentration (2*c1-trih).<br /><br />I did the same calculus, but instead of defining a discharge, I worked with a .ini file and the tracer concentration "c1" in a grid point close to (M,N). At the initial instant "t0" I can observe ,in the trim file, that the defined "c1" is the same as "c1-trim" in the spill point. <br /><br />My questions are,<br /><br />1) When defining a discharge of a tracer in a specific grid cell, in the results of the concentration of this tracer: which is the relation between the defined concentration of the discharge ("c1") and the concentration in the grid cell ("c1-trih")? Which is the "reference time" I should work with (time-step vs time history?) ?<br /><br />2) Is correct to suppose that, when using .ini file, the concentration is referred to the total volume of water in the grid cell?<br /><br />Thanks in advance,<br />Miguel Á.Miguel Reyes2015-09-15T14:29:37Z