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About EricXu

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  1. That's interesting. Are the simulations completed for the same duration? Are there any results writing warning messages in tlf? Possible to upload your model to a network storage for others test? Cheers, Eric
  2. Thanks, Paul. As we know, TUFLOW GPU removed some 2D modelling features which are supported in TUFLOW CPU. We do not know which features are still there and which features have been removed. We do not have time to test every feature to check its exist. We think that this information will be included in the TUFLOW GPU documentation once officially released. My apologise to TUFLOW Support team for my too early question as TUFLOW GPU has not been officially released. We understand that TUFLOW GPU development team are busy with the final documentation for the GPU module. We are looking forward to seeing the official release of TUFLOW GPU. How IL/CL works for 2d_sa_rf layer and material file in TUFLOW CPU (as mentioned in my initial post) is still my interest. We may test it for certain confidence. But, if possible, better to get official answers for fully confidence from TUFLOW Support team. Regards, Eric
  3. Dear TUFLOW Support, If we specify IL/CL in both 2d_sa_rf layer and material file, will TUFLOW CPU count the rainfall loss based on the IL/CL in both 2d_sa_rf layer and material file? Or only one works? If only one works, which one works? From TUFLOW GPU documentation, I understand that TUFLOW GPU will not use IL/CL in material file. Will TUFLOW GPU be able to use IL/CL in 2d_sa_rf layer? Thanks, Eric
  4. Hi Bill, So the third side pipe will not cause a nomral manhole to be created if we assign the "J" type (Junction) manhole for the no chamber junctions. Thanks, Eric
  5. Just could not understand item 48 of TUFLOW Build 2012-05-AA release notes: The release notes said that "Previously, a junction (ie. there is no manhole chamber) was assigned to a node where there was only one inlet and one outlet culvert and they were large in size (ie. negating the need for an access manhole). This caused a problem if a third culvert, such as a small side pipe draining a pit, entered the node. The side pipe caused a manhole to be created, thereby causing significant losses due to the expansion and contraction of flow in the manhole chamber." Junction is a type of manually defined manhole. TUFLOW manual said that "A manhole in a 1d_mh layer will override any automatically created manhole." Why does the third side pipe cause a normal manhole to be created? Thanks, Eric
  6. Hi Bill, Thanks for your clarification on how the TUFLOW engine to work out the flow width and the number of BC side walls. If the BC side walls are calculated in the above way (i.e. cells' size divided by the culvert width), I will think that the unit form loss (for polygon option) and flow length also use the cells' size instead of the actual FC/LFC shape width. I previously did a bridge modelling by using LFC. I used the total form loss divided by the actual bridge width to get the unit form loss. Now, looks I should use total form loss divided by the cells' length to get the unit form loss. This also won't give acurate unit form loss and flow length, just like the flow width and number of side walls for BC without changing BC_Width and applying appropriate pBlockage. Is it possible for TUFLOW to capture and use the flow length and flow width from the actual FC/LFC shap? Then TUFLOW will also work out correct number of BC side walls and unit form loss. This may be not so important for large scale flood modelling, but may be important for detailed structure modelling. Cheers Eric
  7. Hi David, I am not TUFLOW, but be able to answer your first question. You do not need to enter the culvert numbers. The 2D shape length will tell the total FC length. (The culvert numbers) = (the total FC length)/(The width you entered). Then TUFLOW can correctly calculate the side wall friction. Tuflow should scale the cell's friction and form loss etc if the banks of culvert width is less than the grid size. I assume so, but not 100% sure. Only TUFLOW can answer this. Anyway, for that case, you'd better to model the BC with 1D approach. Are you the David Franklin I met 3 years ago? Cheers, Eric
  8. Hi PHA, The 'H' in QH curve for weir/orifice flow is the water depth on the 2d dells around the field inlet which is different from the water level on/above/below the field inlet. Say there may be 50mm deep water on the 2d cells around the field inlet, but the water level in the field inlet may be 1 meter below than the field inlet. In this case, the field inlet is not submerged. See figure 7.05.4 and 7.05.5 in QUDM (Queensland Urban Drainage Manual) for the 'H' in QH curve of weir/orifice flow and water level on/above/below the field inlet. I think that we have different understanding about "WHEN". I mean we do not know "at what time" each field inlet is submerged. This time only can be caught by Tuflow during the simulation, and the flow calculation should change from weir to orifice at this time for the submerged field inlet. Of cource, we know that once the water level on the ground goes above the field inlet, the flow changes from weir to orifice. Regards, Eric
  9. Hi Dan, If you 'take an envelope of these to form the combined inlet curve', you will just use the graphic cross point between the weir curve and orifice curve as the flow changing point. But at this point, the water surface level may be much under or above the field inlet level, which is not the appropriate water level for flow changing from weir to orifice. Only the Tuflow model knows when each field inlet is submerged, and when the flow type should be changed from weir to orifice for each field inlet. Thank you very much. Regards, Eric
  10. Hi Paul, That's a great idea for the horizontal field inlet. An issue regarding the transition point between weir flow and orifice flow is: To "take an envelope of these to form the combined inlet curve" is purley mathimatic data processing, you will just use the graphic cross point between the weir curve and orifice curve as the flow changing point. But at this point, the water surface level may be much under or above the field inlet level, which is not the appropriate water level for flow changing from weir to orifice. QUDM says that "For shallow depths the flow will behave as for a sharp crested weir. For greater depths the inlet will become submerged and inflow will behave as for an orifice". So Tuflow may need to add a switch for flow transition based on water level (ie when the field inlet is submerged). It is better for Tuflow to add additional fields for width and height of the field inlet, so Tuflow can solve field inlet (horizontal) just same as kerb inlet (vertical). Tuflow may need a different layer for field inlet or define a flag for field inlet in 1d_nwk layer. It's just personal suggestion to BMT_WBM. Thank you very much. Regards, Eric
  11. Hi Yau, For your case, the L1_FLC/m is 0.2/10=0.02, the L1_FLC/cell is 0.2/10*cell size. Instead of setting L2_FLC=0, the manual says that "Layer 2: The bridge deck. This would be 100% blocked and the form loss coefficient would increase due to the additional energy losses associated with flow surcharging the deck" I have a question for this topic is : If we use layered flow contractions to model the bridge, how does Tuflow consider the impact of the blockage like the bridge deck and handrail? Will Tuflow consider the blockage impact only by applying form loss coefficient (L1_FLC, L2_FLC, L3_FLC, ) or will Tuflow calculate the pure blockage separately in addition to the form loss? If so, how does Tuflow calculate the pure blockage? Regards, Eric
  12. Hi all, For C,R and W Type pit, the Tuflow manual says that they are weirs (in the vertical) . Does the vertical weir mean field inlet or kerb inlet? My understanding is kerb inlet. Once the water level goes above the kerb inlet height, orifice flow equation will be used. If this is correct, how shall we input the width and height for field inlet in order for Tuflow work for both weir and orifice flow? Thanks in advance. Regards, Eric
  13. Hi Phillip, Thanks for your reply. I checked the sh_obj_check layer and the tlf file last night. I could not find any problem from there. I ran the model several times by removing xf8 files created previously. I even shut down the computer in case that Tuflow remembered previous tins. Regards, Eric
  14. Hi All, We have a Tuflow model using 1D irregular Culvert whose behaviour is not good. We have tried both XZ and HW table to define the culvert cross section shape. Also tried different time step. But could not get a good model performance. When we tried to use Zig-zag SX line to connect more cells to the 1d culvert, we only got a good model performance for very low flow. We have to use 2d_lfcsh layer to model the irregular Culvert which is suggested by Phillip Ryan. This worked well. Sometimes, we may have to use 1D irregular Culvert with good cross section definition. Does anyone else have same problem with 1D irregular Culvert? Any one solved the problem? Thanks in advance. Regards, Eric
  15. Hi All, Does anyone have problem with 'Read GIS Z Shape == 2D_Zsh.MIF'? I used a polygon ('Z=0,dZ=0,Shape_Width_or_dMax=0,Shape_Options= ') without any points to snap its vertices. But the vertices actually were not merged with the current Zpt values, so I could not revise all the Zpts within the polygon.I also tried 'Shape_Options=MERGE ALL', but the same result. Before the 'Read GIS Z Shape' command, I used six 'Read Tin Zpts' commands. I don't think this will cause the above problem, but I could not find anything special with this TGC file. I used 'Read GIS Z Shape' for another Tuflow model with the exactly same 2d_Zsh table, which worked well. Sometimes we have to use 2d_Zsh to modify the Zpts since we only have 1 12D dongle in the group. Thanks in advance. Regards, Eric
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