# sediment scour

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 October 22, 2012, 20:28 sediment scour #1 Member   bird Join Date: Sep 2012 Posts: 42 Rep Power: 6 All dears, Hi, I am trying to use sediment scour model to simulate the scour patter around a vertical cylinder under steady flow. And here are my quetions: 1. I know the meaning of critical and cohesive sediment fration, but I don't know how to define the values of them. 2. As we all know, we can define the seabed by--initial--fluid region--the sediment concentration--packed, here the value of packed=density of the sand(for example 2.65)*solid fraction of the sediment? And if it is true, so how to define the value of solid fraction of sediment(1? or 0.9?and so on). 3.In the fluid region, we also need to define the fraction of the fluid, if the solid fraction I input is 0.9, so the fraction of the fluid should be 0.1 of 1? When I choose 0.1, after the simulation is run the fluid above the seabed drops straightly down to the "seabed", but when I choose fraction of fluid=1,there is no problem, but I don't think it is reasonable(can there be such large amout of water in "seabed"?), so how to define the value of "fraction of fluid"? 4.After the simulation is done, how can I see the flow pattern in the tab "Analyze"? Is it like this: iso-surface--packed sediment concentration; color variable--strain rate? But I can't find more detailed information, for example the scour depth. I will be grateful is someone can help me.

 October 23, 2012, 10:59 #2 Senior Member   Jeff Burnham Join Date: Apr 2010 Posts: 204 Rep Power: 9 FLOW-3D v9.4.x includes packed sediment depth and rate of change in depth as output variables that can be used as the color variable when plotting packed fraction as the iso-surface. If you have an earlier version than that, you may have to experiment to find a good way to plot.

 October 23, 2012, 11:02 #3 Senior Member   Jeff Burnham Join Date: Apr 2010 Posts: 204 Rep Power: 9 The solid fraction of the initial regions is the same as the 'maximum packing fraction' defined on the Physics dialog for the scour model. The different proportions of sediment are used to calculate the fractions of each species in that already-known solid fraction. Always set the fluid fraction = 1.0; even in the initial fluid regions: the sediment (both suspended and packed) is considered a two-phase mixture fluid, and that fluid must be 100% present (F = 1) in all submerged cells, otherwise there will be many pressure failures and collapse of the fluid.

October 23, 2012, 20:00
#4
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bird
Join Date: Sep 2012
Posts: 42
Rep Power: 6
Quote:
 Originally Posted by JBurnham The solid fraction of the initial regions is the same as the 'maximum packing fraction' defined on the Physics dialog for the scour model. The different proportions of sediment are used to calculate the fractions of each species in that already-known solid fraction. Always set the fluid fraction = 1.0; even in the initial fluid regions: the sediment (both suspended and packed) is considered a two-phase mixture fluid, and that fluid must be 100% present (F = 1) in all submerged cells, otherwise there will be many pressure failures and collapse of the fluid.
Thank you JBurnham, you have helped me many times.

 April 25, 2013, 05:49 #5 Member   mahdi Join Date: Jan 2013 Posts: 43 Rep Power: 5 Hello pyxbird & JBurnham I simulated a channel with movable bed by v10. Could you please tell me that how can I take a plot of bed deformation and also How can I obtain maximum depth score in results file? I would be thankful if you help me.

May 2, 2013, 15:20
#6
Member

mahdi
Join Date: Jan 2013
Posts: 43
Rep Power: 5
Quote:
 Originally Posted by pyxbird All dears, Hi, I am trying to use sediment scour model to simulate the scour patter around a vertical cylinder under steady flow. And here are my quetions: 1. I know the meaning of critical and cohesive sediment fration, but I don't know how to define the values of them. 2. As we all know, we can define the seabed by--initial--fluid region--the sediment concentration--packed, here the value of packed=density of the sand(for example 2.65)*solid fraction of the sediment? And if it is true, so how to define the value of solid fraction of sediment(1? or 0.9?and so on). 3.In the fluid region, we also need to define the fraction of the fluid, if the solid fraction I input is 0.9, so the fraction of the fluid should be 0.1 of 1? When I choose 0.1, after the simulation is run the fluid above the seabed drops straightly down to the "seabed", but when I choose fraction of fluid=1,there is no problem, but I don't think it is reasonable(can there be such large amout of water in "seabed"?), so how to define the value of "fraction of fluid"? 4.After the simulation is done, how can I see the flow pattern in the tab "Analyze"? Is it like this: iso-surface--packed sediment concentration; color variable--strain rate? But I can't find more detailed information, for example the scour depth. I will be grateful is someone can help me.

Hello pyxbird
Could you please send me your prepin file.
Because I want to do same study.
I would be thankful, if you can help me.

May 8, 2013, 02:59
#7
Member

bird
Join Date: Sep 2012
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Quote:
 Originally Posted by mahdi1 Hello pyxbird Could you please send me your prepin file. Because I want to do same study. I would be thankful, if you can help me.
Sorry I didn't surf the Internet in the past days, I simulated that case last year and the prepin file is lost. And I will continue the work few months later.

May 8, 2013, 03:07
#8
Member

bird
Join Date: Sep 2012
Posts: 42
Rep Power: 6
Quote:
 Originally Posted by mahdi1 Hello pyxbird & JBurnham I simulated a channel with movable bed by v10. Could you please tell me that how can I take a plot of bed deformation and also How can I obtain maximum depth score in results file? I would be thankful if you help me.
Firstly you should define a bed in Meshing&Geometry, and after the simulation is done, in Analyze Tab, 3D, you can find the bed height directly.

 May 15, 2013, 11:30 A case caused by stokes wave acting on a mobile bed #9 New Member   周傳傑 Join Date: May 2013 Posts: 3 Rep Power: 5 Hello everyone, I am a Flow-3d 10.0 user. I am simulating a scour case caused by stokes wave. The simulation is no error and warning, i want to show the mobile bed in the same way with the figure.2 ( from this address: http://www.flow3d.com/resources/news...our-model.html ) I have already tried the Packed sediment height and the Total sediment solid fraction, but it didn't work. In Physics-the sediment scour, i only changed the quality of Diameter and Density, is it right? In output, i only choose the Fluid velocity, Hydraulic data and Sediment concentration. Is there anything i didn't notice? I also want to take the data of bed height, what option should i take? Please do me a favor, i appreciated!!!

 May 15, 2013, 13:50 #10 Member   mahdi Join Date: Jan 2013 Posts: 43 Rep Power: 5 Hello elite about graphical output: I have same problem too. But you can see bed deformation as follows: Specify a name for sediment species, after that, you can find this name in Analyze, 2-D, Counter variable ,.......... choose it no velocity vector for vector type Render This is a way to see bed deformation. If you could find another method, please inform me. about diameter and density, you can do a sensitive analysis according to below paper: http://www.flow3d.com/pdfs/tp/wat_en...ions-07-13.pdf

May 16, 2013, 05:35
#11
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Thank you, Mahdi.

I took your advice to analyze the simulation,
but the results don't look like the pics from the website i posted last time.

Why can't it be as clearly as the fig.2?
I would like to make my mobile bed showed in one color with boundary line.

Whether the failure reason is that i didn't choose the enough items in output data before simulate?
If yes, what should i take?

Thanks a lot for your paper about the density and diameter.
It do me a big favor!!!
Attached Images
 frame0051.jpg (82.3 KB, 60 views) frame0156.jpg (81.2 KB, 41 views)

May 16, 2013, 16:46
#12
Member

mahdi
Join Date: Jan 2013
Posts: 43
Rep Power: 5
Quote:
 Originally Posted by elite1989 Thank you, Mahdi. I took your advice to analyze the simulation, but the results don't look like the pics from the website i posted last time. Why can't it be as clearly as the fig.2? I would like to make my mobile bed showed in one color with boundary line. Whether the failure reason is that i didn't choose the enough items in output data before simulate? If yes, what should i take? Thanks a lot for your paper about the density and diameter. It do me a big favor!!!
Hi
As I told you before, I have same problem too.
If you could find a solution, let me know.

Regards,
Mahdi

May 16, 2013, 17:31
#13
Member

mahdi
Join Date: Jan 2013
Posts: 43
Rep Power: 5
Quote:
 Originally Posted by pyxbird Firstly you should define a bed in Meshing&Geometry, and after the simulation is done, in Analyze Tab, 3D, you can find the bed height directly.
Hello

Thanks for your reply.
I have a big problem yet.
I simulated local scour around pier. But my results don't seem to be correct. (please see attached picture).
I also attached my prepin file. I would be thankful if you tell me what my mistake is.

I really appreciate any help you can provide.
Attached Images
 Capture.JPG (27.1 KB, 111 views)
Attached Files
 aaaa.zip (15.7 KB, 69 views)

 May 21, 2013, 08:46 #14 Member   mahdi Join Date: Jan 2013 Posts: 43 Rep Power: 5 Hello elite Do you have experience about local scour around pier?

May 21, 2013, 16:05
#15
Member

mahdi
Join Date: Jan 2013
Posts: 43
Rep Power: 5
Quote:
 Originally Posted by pyxbird All dears, Hi, I am trying to use sediment scour model to simulate the scour patter around a vertical cylinder under steady flow. And here are my quetions: 1. I know the meaning of critical and cohesive sediment fration, but I don't know how to define the values of them. 2. As we all know, we can define the seabed by--initial--fluid region--the sediment concentration--packed, here the value of packed=density of the sand(for example 2.65)*solid fraction of the sediment? And if it is true, so how to define the value of solid fraction of sediment(1? or 0.9?and so on). 3.In the fluid region, we also need to define the fraction of the fluid, if the solid fraction I input is 0.9, so the fraction of the fluid should be 0.1 of 1? When I choose 0.1, after the simulation is run the fluid above the seabed drops straightly down to the "seabed", but when I choose fraction of fluid=1,there is no problem, but I don't think it is reasonable(can there be such large amout of water in "seabed"?), so how to define the value of "fraction of fluid"? 4.After the simulation is done, how can I see the flow pattern in the tab "Analyze"? Is it like this: iso-surface--packed sediment concentration; color variable--strain rate? But I can't find more detailed information, for example the scour depth. I will be grateful is someone can help me.

Hello pyxbird

Could you please post your prepin file about local scour around pier.
Because I am also working on that. I need your experience to create my model.

I really appreciate any help you can privide.

May 25, 2013, 02:06
hi Mahdi
#16
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Quote:
 Originally Posted by mahdi1 Hello elite Do you have experience about local scour around pier?
I am sorry, Mahdi.
My lab just have some experiences about the scouring on seawall.
I have a prepin file from my friend, it's about the scouring around pier.
Do hope it will give you a hand.

Have a wonderful weekend.
Attached Files
 Outlook.zip (8.0 KB, 93 views)

May 27, 2013, 07:21
#17
Member

mahdi
Join Date: Jan 2013
Posts: 43
Rep Power: 5
Quote:
 Originally Posted by elite1989 I am sorry, Mahdi. My lab just have some experiences about the scouring on seawall. I have a prepin file from my friend, it's about the scouring around pier. Do hope it will give you a hand. Have a wonderful weekend.

Hello elite

Thanks for your file.
Did you see results of that file?
That file is according to below paper and its results are different with results of this paper.
http://www.flow3d.com/pdfs/tp/wat_en...flow-23-09.pdf

Do you know that what is because of this difference?
or Could you please ask your friend about that?

Also Do you know that how I can obtain maximum scour depth exactly?

Thanks

June 1, 2013, 23:26
#18
Member

bird
Join Date: Sep 2012
Posts: 42
Rep Power: 6
Quote:
 Originally Posted by mahdi1 Hello pyxbird Could you please post your prepin file about local scour around pier. Because I am also working on that. I need your experience to create my model. I really appreciate any help you can privide.
Sorry, my prepin file is deleted. Because I ran the simulation last year, and the result was bad. And I am not good at this part, I am sorry. But later maybe in July I will focus on sediment scour, after I learn more about it, and t I can discuss it with you.
Bird
June 2nd, 2013

August 10, 2013, 15:12
sediment Hight
#19
New Member

hossein
Join Date: May 2012
Posts: 25
Rep Power: 6
Quote:
 Originally Posted by JBurnham FLOW-3D v9.4.x includes packed sediment depth and rate of change in depth as output variables that can be used as the color variable when plotting packed fraction as the iso-surface. If you have an earlier version than that, you may have to experiment to find a good way to plot.
Dear Sir,
I am using Flow3d V9.3.2 for simulating scouring. How can I measure sediment height and scour profile at Flow3d V9.3.2?

Thank You

 December 10, 2013, 10:22 scour under submarine pipeline #20 New Member   Join Date: Dec 2013 Posts: 6 Rep Power: 4 I Model a submarine pipeline in flow3d, but it doesnt show any scour under pipeline, it will appreciate if you could help me to find out whats wrong with my model. & also which out put is useful in scour models? sycst911 and ludosbiz like this.

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