ANSYS Fluent Tutorial: Sudden Contraction With Variations in Outlet Boundary condition
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- เผยแพร่เมื่อ 18 ต.ค. 2017
- This is an analysis of sudden contraction of a pipe and the flow physics near the contraction region.The formation of "Vena Contracta". The variations in velocity and pressure. Various outlet conditions are observed and compared.
- วิทยาศาสตร์และเทคโนโลยี
![[CFD] Pressure-Inlet Boundary Conditions](http://i.ytimg.com/vi/Er2j5Kq17as/mqdefault.jpg)
i watched video, that is very good to learnt fluent. please upload some videos about acoustics effects due to design of the
pipe
bhala thevi bhira oka dil khush kr dita hai ....mitha samny hovein haan na ta tera matha chum ghina han lekin kher wt e bteda bara bara bhala thevy tein sada project complete krwaya e .......Allah teno bao deve Allah tedi hayati kry Allah tede baalan no khush rakhy ....
I did not understand Punjabi, but still I understood what you said. Thank You. 🥰🥰🥰
@@AnsysTutor haha but the problem is our project was to calculate minor loss coefficient k and in this video you have selected smaller pipe of 600mm that includes friction factor.
good day. Would you can say to me, what are mean [open shear transfer coef ]. And
mathematical expression for this coefficient.Thank
what if i have like a 300kPa inlet and 10m/s velocity and want to know pressure at outlet
This is a great video. But can you please explain why did you change boundary conditions and compared the results of your velocity at different boundary conditions? At first instance, it was Pressure at Outlet, at second instance, it was Outflow at Outlet and at third instance, you kept outlet vent - I really wondered what could be rectified or studied from this comparison?
Secondly, say if I have a pipe which has one inlet and two outlets, and I want to find whether the fluid flow is distributed equally or not into two pipes, then what should be my boundary condition at outlet? Because this is little confusing after watching this video. Should it be outflow or anything I can keep? Your response will be highly appreciated! Thank you!!
This video was a request from a viewer to compare different boundary conditions at the outlet, that why we have made the tutorial like that. And for the second query: you can take any outlet boundary condition as per your requirement, generally people take pressure outlet if there is any problem then can take outflow boundary condition.
I have tracked the tutorial was so beneficial thank you . I'm stuck with wall shear stress how I can chart it correctly ?
Chat option is available in the CFD post processing part, You can select the location where you want to see the shear stress.
Thanks for the video. I have a question about the results. Why does pressure become negative at the corners right after the contraction?
It might be due to the eddy formation.
Thank you for ur tutorial. i wud like to ask about an issue i am encountering after meshing. even though mesh and geometry are ticked green, set up is still displaying question mark. may i know why that could be? (i have followed the tutorial at all steps)
You should reset the setup, and put the boundary contions to do the solver setup again. This happened Because you might have left the setup process in between and closed the file before initialization or running the simulation.
We would really appreciate voice in background. Thank you.
We are trying to upload or next videos with voice . Thank you for your comment .
what are the values of pressure at inlet and outlet?
At 16:30 the pressure contour has been shown. If you want at inlet & outlet you need to find out it from fluent results. From Facet average or line integral value.
Excellent, but it became rectangular channel rather than pipe as you did not change it from planer to radial in general setting. If it is intentional for rectangular channel then ok otherwise I think it should be adjusted. I may be wrong. Please make me clear this point. Thanks. you are doing awesome jobe
For Axisymmetric case we can do like that, making a half of the pipe then selecting an axis ,and choosing Axisymmetric in the general setting , But in this case its 2d pipe, all the results are in integral form , so you can consider it as circular c/s or rectangular c/s that does not matter. There is nowhere you can select radial option in ansys fluent as there is no such option. Only 3 option planer , Axisymmetric and Axisymmetric swirl.
@@AnsysTutor thanks. keep it up your excellent job
I have a project for the same case can you share me the mesh file
This is a very simple 2D geometry ,We have shown in this tutorial how to mesh it . Please go through this .If you are facing any difficulties in meshing then please reply we will try to resolve that.
could this be solved with the concept of axisymmetric?
Yes. Only you need to modify the geometry to half, and assign axis boundary condition to it.
Hi, i really like your explanation, i am also working on the same project but major difference is sudden expansion . Moreover i know the outlet velocty (for example 20 m/sec), and inlet boundary condition is atmospheric pressure(i.e pressure inlet). so my doubt is How can i take the boundary condition in Ansys Fluent ?, because in Ansy Fluent we don't hvae outlet velocity boundary condition, could you please help me
you can enable "target mass flow rate" option in pressure outlet menu, and let the inlet as "inlet vent" . As per the data available to you, You need to calculate the outlet mass flow rate then proceed as I said.
Thanks for your replay, actually i am doing 2D simulation, I know about "target mass flow rate " option but i am bit confused to calculate mass flow rate for my geometry. Because at the outlet i have tube ( outlet face - circular cross-section i.e area of the circle is π (radius)2 ). Generally mass flow rate = density* velocity* cross-section area). But in 2D we don't have face of the circle. we only have one line in our geometry. How can i calculate.
For your information. I know inlet boundary condition (atmospheric conditions i.e default pressure inlet). and i know outlet velocity ( 20 m/sec). I want to know what is the use of "Inlet vent" boundary condition
like i said i have calculated the mass flow rate (by keeping 3D geometry in my mined). And i have taken target mass flow rate at the outlet and default pressure-inlet as inlet boundary conditions, After performing the simulations i checked velocity at the outlet ( from Reports; surface integrals; Area weighted average; velocity). But i got velocity value at the outlet is 1.59 m/sec. i.e Generally i want velocity at outlet 20 m/sec. Finally what i understood is,i have calculated wrongly (mass flow rate).
Could please tell me where i had made a mistake.
do you know what is the inlet velocity? Pressure inlet boundary condition will ask you the inlet velocity ,if you don't know the inlet velocity you can take it as inlet vent.
Thank you for your replay , i have seen the previous message. could u please see the previous msg and then given me your opinion.