Apologies, as I can see from searching that this is a common question, but I'm still in my first week of using Mathcad. I am using the Colebrook White equation to find the friction factor of a pipe. The solver has returned an answer, but I am unable to find how to use this answer in the rest of my worksheet. I have defined my roughness, diameter and reynolds number already - and want to use the friction factor in subsequent formulae.
Many thanks in advance
Solved! Go to Solution.
Your solve block is set up incorrectly.
You say you have calculated Reynolds number - then it must be above the Solve block and all other variables used in the Solve block.
Thanks for your reply Mike. Your solution seems to be working well, but is it possible to calculate separate friction factors for both pumping and generating? I know these will be virtually identical, but it's for a Master's project, so not a real world scenario. Would I need 2 solve blocks to achieve this?
Just played with it and got it to work with one solve block, many thanks!
No problem Mark, glad your got the answer.
Mike, thanks for your help previously. I have now edited some of the preceding formulae, turning them into matrices to enable a sort of parametric approach. However this has stopped my solve block working. How do I enable my solve block to return an answer in matrix form? I had a look at previous forum posts but was unable to decode the answer!
Mark McMullan wrote:
How do I enable my solve block to return an answer in matrix form?
Use an index (a range variable) to get them automatically calculated one at a time. See attached.
Hi Alan, thanks for that. I have tried to apply that logic, and yet again have come across another stumbling block that I can't figure out! The turbine power (Pt) doesn't seem to vary correctly. I would like to alter the reservoir volume (Vru) and the elevation difference (delta_h) and get a 5x5 matrix of the other calculations (such as Pt). That would inform me of the optimal reservoir and head combination. Do you know what I've done wrong?