Simulation of open channel flows in ANSYS Fluent | 15 | Implementing the CFD Basics

[@haseebkhawaja1050]

Excellent explanation. The only good video on open channel flow which explains everything. Much appreciated

[@absarahmedkhan2109]

Thank you for sharing your knowledge of Ansys. You have a wonderful channel. I have always appreciated how Indians share knowledge over KZbin. That is the most beautiful part. Keep it up :) From Pakistan.

[@TanmayAgrawal7]

Thank you so much for watching the video and your generous comment. Regardless of nationality, I believe everyone should share their knowledge :)

[@engineeringsimulationstudi1404]

kzbin.info/www/bejne/aGqzlYNuZpmroa8

[@sukhjindersinghghunder7569]

Sir, I have question, what about gravity when our channel bottom surface is inclined . At that time the gravity will act vertically, while it should act as perpendicular to the surface

[@benedicta8237]

Hello sir, thank you kindly for the teaching. I'm wondering, how can I extract information of wave height at particular distance from the simulation? Thank you in advance

[@Anilkumar-fv9zy]

how to find flow depth after simulation has done?

[@mahdiahadiyan7123]

Thank you for your great tutorial. I do all of the instructions like you and get a great result of volume fraction of water and saw the waves in the domain. But the contour of velocity is not great. The velocity at the outlet is very large at air/water interface and at the bottom of the boundary, there is a negative velocity. Negative velocity at the free surface and at the bottom of the domain is acceptable due to the wave and its effect. But the velocities at the outlet boundary are wrong before the wave or its effect arrives at the outlet. I use none wave to test the effect of the other parameters but the velocity is incorrect as well. I use the timeStep as 0.01 as you said in the video and I set the max iteration as 100 per time step but in some time steps, the continuity residual doesn't converge under the 1e-3. What should I do? I want to simulate an oil leakage from a pipe in a 2d scheme but there is a negative velocity like this problem. I think that If you run your problem for more time steps(e.g. 10000 time steps), the result may be incorrect.

[@maysamir8106]

Very helpfull thank you

[@abhishekbihari177]

Thanks for the tutorial sir...Can you please suggest....what conditions should i give to make a body float on the ocean?? e.g. a boat floating due to ocean currents

[@mapo601]

Excellent, thank you !!

[@guanguan7658]

Thanks for this tutorial, sir. I was wondering how could you initialize the conditions for a velocity inlet? Based on the Ansys Fluent Guide, only mass flow inlet and pressure inlet could have this initialization. I also have a velocity inlet and during initialization, Fluent came up with an error that a velocity inlet is invalid.

[@TsewangStanzin_sicv]

Sir we are doing project on, wave attenuation due to submerged breakwater using ansys fluent...we just have to put one structure in between this channel...so our main aim is to reduce the wave height and wave velocity...so to calculate this height and velocity of wave, some probe has to put..how to put this probe sir... please help

[@narendrakumarpatel6910]

If we include bed slope then free water surface level would be different than 0.2 at different locations. How we can consider that? I didn't get what is driving force in this problem if slope is not considered?

[@sachusss495]

sir can you please add design of rectangular tank and which solution method is using. while I running it the reversible flow comming and #f error is comming. can you please give suggestions for clear these errors

[@Anurag-sq4yc]

Sir can you make tutorial for 3d open channel

[@junaidaminhrp]

thank u sir @Tanmay Agrawal for this awesome tutorial ..i hope this tutorial will help to solve my final year project .. sir i have a question ..how can i vary water level in open channel and find different flowrate values against it ?

[@engineeringsimulationstudi1404]

kzbin.info/www/bejne/aGqzlYNuZpmroa8

[@kushbudhathoki4420]

Dear Sir, Please provide me suggestions. I am doing study focusing on pressure and velocity variation in u/s and d/s of a weir across river using 2D fluent model. The weir is 14.6 m length from u/s to d/s and 9.0 m height. I have taken domain size of total length 414.6 m (300 m u/s, 14.6 m weir and 100 m d/s). The height of domain is 40 m. For boundary conditions, inlet is assigned as velocity inlet, outlet as pressure outlet and free surface as pressure outlet. I assigned water as primary phase and air as secondary. The depth of water at inlet is 11.5 m. Is same depth should assign at outlet? Moreover, I could not refine my mesh than element size less 0.4 m. Reverse flow occurring in many cells during solution. Also I have confusions with time steps and time step size.

[@repackgames8464]

I am not able to create a chart of surface elevation vs time in post processing after putting a proble in the domain

[@repackgames8464]

Plese help.us out here

[@mesuttekgoz7076]

How to proceed to the 6DOF object, with this set-up, thank you

[@rama0625]

@Tanmay Agarwal, could you please make a tutorial on buoyant jet in a stratified environment. Thanks in advance.

[@TanmayAgrawal7]

Hi! I'll try to find some time and suitable example. Are you a student of Prof. Balasubramanian?

[@rama0625]

@@TanmayAgrawal7 I have replied you in your email id [e-mail]

[@ogremighty8895]

how can vertical excitation of the tank be made in fluent, please?

[@tamsdienye4360]

What is the value for ''monitor check convergence absolute criteria'' that is Residual Monitor.Also what is the solution methods and spatial discretization you used

[@TanmayAgrawal7]

Everything if I remember correctly is set to default

[@SailajaPoudel2024]

hi, can I use pressure inlet as inlet BC and outflow as outlet BC ? Can You explain in which cases I can use pressure inlet and Outflow boundary condition. Thanks in Advance.

[@TanmayAgrawal7]

From what I remember, outflow shouldn't be used when using pressure inlet as inlet BC

[@katungumunyaradzi2254]

How do you simulated a hydraulic flume with a roughened bed

[@markkeating3522]

Use a code dedicated to 3D hydraulics modeling

[@shindiregitasyali9248]

This is an excellent tutorial. However, I have a problem with volume water friction, it won't show the right contour. Can you help me? Thank you

[@TanmayAgrawal7]

Can you please email me with more details? [e-mail]

[@engineeringsimulationstudi1404]

kzbin.info/www/bejne/aGqzlYNuZpmroa8

[@tamsdienye4360]

Thanks for this wonderful simulation. I want to simulate a slug flow in a 2D pipe. Do I consider it as closed channel or open channel. Can your simulation help me achieve a slug flow regime, where the wave will get to the top of the 2D pipe. Please help direct me

[@engineeringsimulationstudi1404]

kzbin.info/www/bejne/aGqzlYNuZpmroa8

[@lakshithranasinghe]

Hi Tanmay, Thanks for the video, its content is invaluable. Im currently working on a simulation which involves the flow of a river with a mesh blocking the whole river. Im having some trouble with the the setup section. The water is only flowing at 0.23m/s and I wish to model it without any waves as theres very little in reality on a calm day, so when selecting multiphase flow do I still choose the 'open channel wave BC' condition as well? Or do I tick both options and for the inlet wave multiphase boundary conditions choose none as the 'Wave BC Options' (instead of something like gravity waves). Also, do all multiphase simulations have to be transient, can it not be steadystate as in my case there is very little variation with time. Thank you :)

[@TanmayAgrawal7]

Hi, Sorry for the delayed reply. As far as I know, open channel wave BC is used to define the kind of waves in the setup and you can use the same tool to initiate very small waves. It should still be alright with the physics of your problem. Mostly problems are transient because of the interaction between different phases but some problems could achieve steady state, no doubt about that.

[@lakshithranasinghe]

@@TanmayAgrawal7 thank you for your reply :)

[@markkeating3522]

I would try and use a code that is dedicated to hydraulic flows as these give all the correct options (eg for hydrograph inputs) for setting up such cases

[@subhampal1156]

Sir I really appreciate the tutorial . I tried following the exact same procedure but while running calculations I keep getting oscillating residuals graph even after 1 hour (25000 iterations) . I also tried changing the geometry to smaller dimensions but still the same problem. Could you please help me with this ?

[@TanmayAgrawal7]

Did you check the solution? In unsteady cases, that might happen based on my experience.

[@subhampal1156]

@@TanmayAgrawal7 sir the solution was awesome . Sorry sir , initially did not check the solution . Later I too understood that since its unsteady flow, residuals will fluctuate . Thanku again sir

[@arhantika8783]

Which model should i use if i have a single fluid in a closed channel. Lubricant inside a journal bearing, to be specific.

[@TanmayAgrawal7]

If it is not a multiphase flow, you can go without it (sorry for the delayed response)

[@arhantika8783]

@@TanmayAgrawal7 but i want to model a nanofluid actually. Nanoparticles of al2o3 in water. And use that as lubricant for bearing. Can i use multiphase mixture for that? Or should i use something else?

[@TanmayAgrawal7]

@@arhantika8783 Perhaps Eulerian model would make sense, but not 100% sure.

[@arhantika8783]

@@TanmayAgrawal7 okay thank you. Do you know how to change the volume fraction of nanoparticles in the model?

[@TanmayAgrawal7]

@@arhantika8783 You can do so when you initialize the flow field.

[@tamsdienye4360]

Hi, please how do I produce this wavy flow simulation for a closed channel with air and water. Also, a stratified and slug flow. thanks

[@TanmayAgrawal7]

For a closed channel, the top surface has to be given as wall. You can not use the open channel wave BC then and have to manually assign the flow velocities as a function.

[@engineeringsimulationstudi1404]

kzbin.info/www/bejne/aGqzlYNuZpmroa8

[@kaushalbaghel603]

i have designed a triangular labyrinth weir in an open channel in a 3d geometry. For open channel, i have used enclosure tool around weir. i am unable to simulate the flow as i dont have much knowledge about setup part. please help

[@TanmayAgrawal7]

Can you please email me with a little more details? [e-mail]

[@kaushalbaghel603]

@@TanmayAgrawal7 i have emailed you the details. please look and reply asap...... thanks in advance

[@engineeringsimulationstudi1404]

kzbin.info/www/bejne/aGqzlYNuZpmroa8

[@mdejoss1311]

Sir how actualy coordinat on free surface work?, Exmple i have slope channel with 0.02m high upstream and 0 m on downstream (outlet), how to set free surface in the inlet and outlet , tank you

[@TanmayAgrawal7]

Define it as free shear in that case, hopefully it should work. Define them as walls and prescribe zero shear on it.

[@mdejoss1311]

@@TanmayAgrawal7 yes but, in tutorial, i see you use FREE SURFACE LEVEL in inlet and outlet to set how high water gona be,(ex. 0 m level free surface in bottom and 0.2 m level free surface on top , this measure must be use coordinat system on object chanal right? But its use local or global coordinat by default ? ).and basicly you have 0.2m high water constant from inlet to outlet right?, But imagine if your open canal is slope, did i just need set high water using free surface level on inlet only or anyting else, my problem is water level on inlet basicly

[@engineeringsimulationstudi1404]

kzbin.info/www/bejne/aGqzlYNuZpmroa8

[@vishnuraja.d6296]

Thanks for the video... I was trying to simulate wave over a cylinder..but the velocity field is bit lower than the experiment data...when checking case fluent shows "review boundary conditions at inlet velocity.default values detected".could anyone help me out of this??

[@TanmayAgrawal7]

Did you use the right wave BC?

[@vishnuraja.d6296]

@@TanmayAgrawal7 yes..I have checked

[@engineeringsimulationstudi1404]

kzbin.info/www/bejne/aGqzlYNuZpmroa8

[@vishnuraja.d6296]

@@engineeringsimulationstudi1404 thanks for the comment.

[@sikandaryosufzai2790]

Thank you sir for the useful tutorial. sir i have a problem iam doing my masters and i have to run 3d model. my project is on energy dissipation downstream of a piano key weir . always i run the model it give me floating error. can you help me please sir. Respect sikandar from Afghanistan. Mtech in (IIT roorkee)

[@engineeringsimulationstudi1404]

kzbin.info/www/bejne/aGqzlYNuZpmroa8

[@sabindangol2779]

How can we input discharge in inlet rather than velocity?

[@TanmayAgrawal7]

I can't remember on the top of head but there is a mass flow inlet boundary condition. Use that instead of velocity inlet and you should be good to go.

[@markkeating3522]

If you have hydrograph data this is a standard input format in (other) 3D hydraulics CFD tools

[@masxertuip]

How long does it take to get the convergence?

[@TanmayAgrawal7]

Shouldn't take too long, depends on the computing power for your hardware. For me, maybe 10-20 minutes, can't remember for sure.

[@bushettyshivakumar7341]

sir iam working on a submarine projectt and i want to make the drowning simulations , can you help me with the procedure and the dynamic mesh selection

[@TanmayAgrawal7]

Sorry, I am not well versed with that.

[@ShivaKumar-ff5px]

@@TanmayAgrawal7 thankyou

[@markkeating3522]

Using a code dedicated to hydraulics, you need not create a body fitted mesh or use dynamic meshing as geometries will glide across the mesh

[@bushettyshivakumar7341]

@@markkeating3522 what type of code sir , can you give me some references please

[@markkeating3522]

@@bushettyshivakumar7341 FLOW-3D HYDRO

[@markkeating3522]

Solving for the gas phase in this simulation is such an unnecessary expense of resource. Just solve for the liquid phase as a one fluid VOF and treat the gas as a fixed pressure.

[@geetasharma1206]

How can I add a sand bed at the bottom of this section and how do assign sand properties like the mean particle size of 0.85 mm.

[@TanmayAgrawal7]

I believe you can use the patch function to do that. Not sure about particle size, perhaps check out the "granular" tab in multiphase section.