Geopak Drainage - Friction Slope

Has anyone had any issues with Geopak Drainage calculating the friction slopes wrong? I have contacted Bently support and spoke with a couple of their engineers, sent them all my data, and they could not seem to figure it out. I even created a spreadsheet to calculate the friction slope "by hand" and prove that something was not being calculated correctly. They were unable to give me an answer and forwarded my concern to their programmers so if there is an issue they will work it out in the next release of Geopak Drainage.

This is very hard to believe that as long as this software has been avaiable, and the professinal nature of its use, that I am the first person to notice this.

On my output (created through Geopak Drainage after running a network) is showing a friction slope almost exactly equal to the slope of the pipe in almost all pipe runs. When the friction slope is calculated by hand, it is much smaller (less than 1 percent)

Any help or comments would be great.

Thanks!
  • Nickoli,

    Friction Slope is that slope (S) in Manning's formula required to convey a specified discharge under uniform flow conditions given a depth, roughness, and shape. Under uniform flow, depth and flow area are constant and the friction slope, the actual slope, and the energy slope are all equal.

     

    You may feel free to email me your details and I will look closer at your assumption. mike.barkasi@bentley.com

     

    Michael Barkasi

    Benttley Civil

    Professional Services

     

    Michael Barkasi

    Application Engineer 

    Reality Modeling



  • Generally if the friction slope is close to the actual slope you'd encounter a 'normal' or 'uniform' flow situation which is most often preferred and it would seem Geopak Drainage is doing its job out of the box. If you're saying your by-hand slope calculations are within 1% deviation of what is being calculated that might be considered close enough, but if you're by-hand calcs are showing less than 1% friction slopes in the pipes perhaps check your Geopak Drainage preferences and ensure you're not impacting the quantity of water directed through the pipes with the options available for Frequency, Intensity & Links; or upload some spreadsheets and maybe someone here can rifle through them ;-)