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nickbartho

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About nickbartho

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  1. Thanks for the suggestions Sam and Paul. Sam - Huxley, 2004 provides a good account of the benchmarking methods used but does not deal in detail with the computations used by TUFLOW/ESTRY. Paul - I am using headwater depth above centreline, not obvert.
  2. Apologies - I posted this as a reply rather than starting a new thread... I have a further query along the lines of previous threads regarding culverts operating under inlet control. For a particular C culvert, TUFLOW is giving us quite different results to that suggested by hand calculation using the orifice equation. For example, the TUFLOW peak flow in the culvert is 13.4 m3/s against a hand calc (with orifice discharge coefficient C = 0.6) of 10.9 m3/s for the same headwater level. The inlet is certainly submerged, and the eof and tsf files confirm inlet control regime L, so I would expect the orifice equation to give a good account of culvert behaviour in this case. I have noted the width contraction coefficient for this particular structure has been set to 0.9 (rather than the recommended 1.0 for C culverts) but I dont see how this would explain the difference - in fact I would expect TUFLOW to produce an even higher flow rate for the higher coefficient. But consideration of this also led me to realise that I dont fully understand how this coefficient is factored into TUFLOW's calculations. This doesnt seem to be covered in the manual, which only refers generally to charts (presumably US-FHWA?) and Henderson 1966, as well as recommended coefficient values. We have forced TUFLOW to match the orifice equation result by adding blockage in this case, but this is obviously not an ideal approach. Is it possible to get a more detailed description of the specific charts and/or equations employed in TUFLOW for culvert calculations, and how these are modified by the H and W contraction coefficients? I'm sure there is a good explanation for the difference I am seeing, but I just dont have enough detail to know exactly what TUFLOW is doing. Cheers, Nick
  3. I have a further query along the lines of this previous thread regarding culverts operating under inlet control. For a particular C culvert, TUFLOW is giving us quite different results to that suggested by hand calculation using the orifice equation. For example, the TUFLOW peak flow in the culvert is 13.4 m3/s against a hand calc (with orifice discharge coefficient C = 0.6) of 10.9 m3/s for the same headwater level. The inlet is certainly submerged, and the eof and tsf files confirm inlet control regime L, so I would expect the orifice equation to give a good account of culvert behaviour in this case. I have noted the width contraction coefficient for this particular structure has been set to 0.9 (rather than the recommended 1.0 for C culverts) but I dont see how this would explain the difference - in fact I would expect TUFLOW to produce an even higher flow rate for the higher coefficient. But consideration of this also led me to realise that I dont fully understand how this coefficient is factored into TUFLOW's calculations. This doesnt seem to be covered in the manual, which only refers generally to charts (presumably US-FHWA?) and Henderson 1966, as well as recommended coefficient values. We have forced TUFLOW to match the orifice equation result by adding blockage in this case, but this is obviously not an ideal approach. Is it possible to get a more detailed description of the specific charts and/or equations employed in TUFLOW for culvert calculations, and how these are modified by the H and W contraction coefficients? I'm sure there is a good explanation for the difference I am seeing, but I just dont have enough detail to know exactly what TUFLOW is doing. Cheers, Nick
  4. Just a few questions about using SMS with TUFLOW: 1. Is the basic Vis package (map+mesh) all that is required for TUFLOW result viewing combined with GIS layers, including creating animations? 2. I assume the grid module isnt required since TUFLOW generates the SMS mesh, or are there benefits to having the grid module as well? 3. Is the TUFLOW interface module useful for results viewing or really just for model build? 4. Are all these questions and more already answered somewhere I dont know where to look?! Would appreciate any other comments/feedback TUFLOW users have regarding SMS too. Cheers, Nick
  5. Just trying to get a handle on any constraints with using a new 1d_nwk layer to modify an existing 1D network by overwriting only selected elements with repeat use of the Read MI Network command. The error I’m getting is “ERROR - Channel X, also occurs elsewhere in the model. Channel ID must be unique. If overwriting, channels must snap to same nodes”. I am (I think) maintaining channel IDs and snapping to the same nodes for the copied elements. Is it also necessary to maintain the geographic location of the original nodes? Are there any other issues to be aware of that I might be overlooking?
  6. Has anyone else had problems getting the longsection tool to work running Vista and Excel 2007? No trouble at all getting this to work on our XP machines but the script bombs on Vista on an "unexpected error 641". This is after it has created and completed the Long_Section_Plot and Long_Section_Plot_Pnts files and after getting past the prompt re Excel and needing to enable macros. Thinking it was an issue with Vista's security settings (along with pretty much every other piece of software we have), we have tried quite a few combinations running Excel as an administrator, with full rights, in XP compatibility mode, different macro security settings etc but to no avail...any ideas would be much appreciated!
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