Scouring Around Bridge Pier
 

Hello To every One

Dear friends I am trying to study local scour around bridge pier and I have tried many differend boundary conditions but I can get logic results my question are
1- I want to set my inlet boundary condition as Inflow ,and I did that also I gave the height of fluid .
2- out let boundary condition pressure with the same height of fluid.
3- fluid region from covers the whole model also I set hydrostatic pressure .
4-i activated all parameters (like sediment scour ,renormalized viscosity, gravity z=-9.8, density
5- fluid density 1000 ,and (viscosity constant =0.001) .
6-i defined my sediment body as packed sediment
but I don't have scour what is the problem can you please tell me??or at least if some has a model just send me your prepn file I will really appreciate it .
one last question what is the unit of finish time is it second ??

finish times unit is second in SI. I think you should change your shields number its really important maybe you do not estimate it correctly because it was my problem and when I change that my problem was solved.

Use of correct parameters
 

We have recently partnered with Friendship Systems for geometry optimization and parametric studies using the software CAESES. For sediment scour modeling, parameters like Shield's Number can be determined using CAESES. Once you have the correct value of Shield's Number from CAESES optimization, you can use that value for your case study.

In fact, we used CAESES internally with a sediment scour problem and got excellent results.

Dear Maryamm thank you very much for your reply you are right I didn't knew my critical shields number but no I know but the problem is I don't have flow happening I think so please can you answer me these two quick questions

1- what's you boundary conditions .
2- do you insert you whole model in the in calculation or you are using symmetry .
3-is defining the particles important or not what does particles are for in physics .
and lastly if you send me your (prepin) it will be a very big favor for me .

Dear Thunde47
Thank you very much I will try that and let you know about the results thanks again

your welcome. I use flow-3d 11 version you can not open it with 10 version but in this photo you can see my model boundary condition. particle is my big problem but with out that you can do your simulation.my model was a small model and I insert hole model but you can insert hole model with 2 size of meshing I did not try and not sure about symmetry.Attachment 46858

Thank you very much Maryammm
actually at the university we have a work station computer and they installed Flow-3D version 11.1 so if you send me your prepin file I can benefit from it really ,I know its not so common but I want to see all the parameter maybe I am having trouble is some where else and I can share my results with you .
thanks again and Best Regards

sorry I could not upload my own model but you can see this prepin file in:
http://www.cfd-online.com/Forums/flo...ent-scour.html

thanks u again you have been very helpful

dear maryamm
can i ask you question
i have two problems
1- sediment grain size is more than **
** 10% of mesh cell size **
** higher ratio of mesh cell size to **
** grain size is recommended
2- if i use big time step value give me error
how can i make simulation for 2 hours with small time step

i'm not maryam :)) but i will answer U
1) first problem does not important at all
But if you want to solve it, U can choose a bigger mesh in sediment part
2) in Tab general, define a little time! for example 10 seconds
and after the simulation start to work, go to the Run time option
and change it to whatever U want!! for example 10000 and then click to send to solver
this make your problem easily solve

Regards,
Hanif:p

Thanks a lot
I will try your advise
Thanks for your help
Can I ask you again about the time step
I will change it or not for big time simulation

Dear maryammm to me your boundary condition can be better by changing in "Y" condition...... my dissertation was about local scour and my research is still on it. I think it should be define as "Symmetry condition".

Dear hanif
pardon me because of my notice, you can not change your time and set it on what ever you want. the time is very important and the right answer is mostly dependent on time because regardless of other part of the SCOUR problem, the equilibrium time plays an important role in local scour. so you should calculate your time with the equations which are related to the balance time

its a trick to reduce the time step size not the entire scour time

Sir, i m doing research on bridge pier scour using fluent. And i m a beginner. So can u please provide me the steps for laying the sand in the channel and steps for meshing in the channel and around the pier. I shall be highly thankful. My email id is "salmanbeg1988@gmail.com". I m waiting for ur reply.

dear eng.
from my knowledge the fluent doesnt have sediment transport model

Hi Sir
I am doing the same work as yours but in openFoam, do you have any suggestion for me as a beginner in this field. I will be very much helpful for this .
Thanks

non-uniform sediments
 

Hi Everyone!

I want to use flow3d to simulate local bridge scour. My case study contains non-uniform sediments and I have understood that flow3d can get different sizes of material.
Have you guys experienced with this specific subject?

Your kind help and advice are most appreciated.