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RE: Specifying the 'design time' in Darwin Designer

Ref: Specifying the 'design time' in Darwin Designer 

Dear Mr. Mal Sharkey,

I tried the method mentioned by you but i get this message :- 

Feasibility check failed. No feasible solution exists with current input data

I have setup EPS by giving the relevant demand multipliers at their respective time zone in :- demand control centers ---> pattern (demand), elipsis ----> Hydraulics ----> new pattern

I wonder where i might be going wrong?

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  • Dear Sushma Choure,

    I thank and appreciate you to analyse the model and help me with this regard.

    Kindly analyse the darwin designer run and guide me as to where i am going wrong.

    Please find the file attached herewith.

    Warm regards,

    ChandrashekharaTippunagar.rar

  • Hello Chandrashekhara, 

    In the model sent there was only one design event, which was set to time from start for 0.00 hours, For testing purpose i created new design event in the same design study with different time from start hours, but couldn't reproduce the error you mentioned. 

    Could you please provide exact steps to reproduce the error? 

    Regards,

    Sushma Choure

    Bentley Technical Suppport

  • Dear Sushma Choure,

    My sincere apologies! it appears that I have sent you a wrong file (older file). Please consider the updated file attached herewith.

    Also, to frame my question properly and for further clarity kindly refer my query from the link :- https://communities.bentley.com/products/hydraulics___hydrology/f/haestad-hydraulics-and-hydrology-forum/170448/presetting-the-velocity-to-a-certain-limitation-so-that-the-diameter-of-the-pipes-are-given-accordingly

    In the above query after guidance from Mr. Joshi, I tried creating selection sets for higher velocities and also the same by creating selection sets for diameters grouped as per their pipe sizes, which has worked well for me and i thank Mr. Joshi for the same.

    However, when I enter 8 hrs in the “Time from start” column I get the error as shown in attached screenshot. But the same design run when computed with an entry of 0hrs in the “time from start” column, Darwin computes successfully.Tippu2.rar

  • Hello Chndrashekhara, 

    If you change the time from start to say 01.00 hrs, 23.00, 24.00 hrs, then you will observe that Darwin Designer does give you the solution. Which means that, the input diameters that you have are not sufficient for the pattern setup for those peak hours e.g. 08.00 hrs.

    So Darwin Designer is not able to find feasible solution even by using the maximum diameter for those time steps. 

    What Designer does in the feasibility check is to use all the largest pipes and see if it can meet the constraints, and if it cannot, it determines that there is no feasible solution.

    To check this go to time-step 08.00 hrs in model and check results for pressures and pipe headloss, you will observer that pressure is still negative and there is headloss for more than 15 m in optimized run scenario i.e. output of Darwin Designer. 

    If you add more pipe diameters in cost properties, Darwin Designer will compute with no error. 

    Also I observed that you have created single design group for each pipe, we would recommend you to create design group for bunch of pipes expected to have equal diameters. 

    I am attaching your model which I have updated with mentioned changes. 

    Tippunagar.wtg.zip

    Regards,

    Sushma Choure

    Bentley Technical Suppport

    Answer Verified By: Jesse Dringoli