• validating SW calculations with Jonswap formula


    I am running a SW model but wave field data for calibration is not available. However I would expect that for a wind velocity of 20 m/s , over a 10 km fetch, Mike would calculate wave heights close to 1 -1.10 m, as calculated with the Jonswap method.  However, the results are in the order of 3 m.

    If I run the uncoupled sea-air option with a Charnock coefficient of 0.004 ( way below the default), I may lower it down to 2.1 m. However, I am not sure if such a low value is realistic.

    Has anyone come across a similar case?

  • Re: Culvert modelling process

    Just to let people know that  I confirmed on my own that's how it works. THe culvert feature only models the hydraulic head loss caused by the culvert inlet, but you have to carve the opening in the scatter data.

    I don't have access to other Mike licenses so I ended up carving the culvert opening
  • Culvert modelling process


    I have the following doubt: It looks like if I want to model a culvert through a dyke, using the Mike 21/3 model, I would have to carve  the river bed in the bathymetric data of the embankment (see attached figure).  I think is not possible modelling the culvert without altering the scatter data. This would mean that if I want to model alternatives where I use 2  and 3 culverts, I would have to modify the bathymetry for each case and the resolution of my mesh has to be as low as the width of the culvert .

    Am I understanding the process correctly?

  • Bed Resistance in Hydrodynamics vs Bed Roughness in Mud Transport


    I am trying to use the Mud Transport module in Mike, which uses as input the results from an hydrodynamic model.  What's the difference between the bed resistance input in the Hydrodynamic Model and the bed roughness input for the Mud Transport model.  Aren't they the same? and if they are not, which one is used in Mike to calculate the bed shear stress?

    Thank you!
  • Extremely high bed mass and net deposition results

    I am trying to model sediment transport in a tidal river over a tidal cycle.  I am using a critical erosion shear stress of 1 N/m2 and a deposition shear stress of 0.001. Settling velocity is 0.2 m/s and as recommended by the software, roughness is 0.001. Density is 500. So I am using pretty conventional values.

    The model is calculating bed shear stress values that oscillate between 0.1 and 8 N/m2. However, the calculations for bedmass and net deposition accumulation result in values in the order of E+004 and E+006 g/m2.  The expected results should be in the order of E+1.

    I have been going over the basics of sediment transport and played with the settling velocity, the roughness, the range of difference between deposition and erosion shear stress without any success.

    Has anyone experienced a similar problem before? Any ideas of what could be causing this problem? or how else could I examine the results to find the cause?

    Thanks you


  • combined effect of swell and wind waves

    Hello there

    So, I am working in a project were I have to take into consideration both: swell and wind waves.  I have a  particular spot were the resulting significant wave height decreases from one time step to the next even though the wind velocity increased in the same interval.  Curiosity led me to model the same mesh under two more scenarios:

    1) Using only swells as boundary conditions (swell mesh)

    2) using only wind forcing. It set the boundary condition for swells to Zero (wind mesh)

    My objective with this exercise was to confirm that the vector sum of the 2 separate models was going to be equal to the significant wave height calculated when both processes were modeled at the same time. To my surprise, after comparing the 3 meshes, it looks like Mike SW actually chooses either one or the other result. There are areas where the "combined mesh results" are very close to the "wind mesh"and some other areas where the combined results are closer to the "swell mesh" (see attachment). Does this make sense? Does Mike 21 SW selects the results after defining some "area of influence"? Am I getting this right?

    Thank you so much for your help

  • Re: Decoupled formulation vs fully spectral

    Thank you so much for your inputs. They were really helpful. I decided to use the fully spectral formulation as I need to study the combined effect of swell and wind waves.

    Thanks again

  • Decoupled formulation vs fully spectral


    I understand that  in Mike21,  the fully spectral formulation the calculations will include processes such as refraction and shoaling, wave growth by the wind, dissipation, etc.. Therefore, I would say that the fully spectral formulation can be used to model nearshore waves. I use this calculations quite often to design armour breakwaters. However, I am not quite sure in which cases is the Directionally decoupled parametric formulation applicable. could someone please help me to understand a bit more this formulation?


  • zero deposition

    I am running the model of a mudflat area where deposition is a big deal. I have a fine resolution mesh, and I am runninig the mud transport extension of Mike 3. I've got my currents calibrated to field measurements but for some reason I am not getting any deposition. I have gone through all Mud Transport input parameters and it doesn't seem that I am inputing any crazy value. The only thing I have to play with to obtain deposition is the bed roughness. Would that be ok? does anyone else have any other suggestion?


  • Mike Zero - Analyse Mesh


    Does any one know the reason why the "mesh analysis" option in Mike Zero, may be grayed out?