gas-liquid slug flow in horizontal pipe
Hello every one, I am a new member. I working on Fluent for modeling a two-phase, gas-liquid (air-water) slug flow in a pipe and I need some help please. My case: pipe length (583cm), (1.27cm) diameter, drawing and meshing by Gambit, the total elements was (112896 cell(, the pipe inlet set to (velocity-inlet), outlet to (outflow), pipe surface to (wall), the pipe continuum to (fluid). In fluent the define sequence as: 1. Solver: pressure based, unsteady, implicit scheme. 2. Multiphase: VOF. 3. Viscous: k-epsilon, standard. 4. Phases: primary as water, secondary as air, interaction: wall adhesion, surface tension (0.07). 5. Operating condition: gravity at y (-9.81), specified operating density. 6. Boundary condition: a. mixture velocity (1.6), k(0.025), epsilon(0.0072). b. air – multiphase volume fraction (1). 7. Initialize: vf=0.18, patch: air vf =0.18. I have a problem I need to get the contour of the slug vf, volume fraction? And, do I need to use a UDF for the velocity?[/FONT]
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gas-liquid slug flow in horizontal pipe
Hi
For the dimensions specified by you, track the flow regime map and then suitable specify the velocity of the gas and water at the inlet. Patching of the secondary phase will increase the speed of the solver towards the solution, otherwise without patching run it from scratch (water filled initially) and define the velocity as a function of time; will give you various flow patterns. Regards mvee |
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Slug can obtained from stratified flow but the point of transporting stratified to slug depend on the phase velocities (especially higher gas velocity give slug flow) hence if you get stratified flow successfully just increase the gas velocity then with progress of the run with time you will get it? furthermore you need to check the range of your phase velocities that fulfill slug flow refer to any flow regime map to check it and I prefer that given by Taitel & Duckler Flow regimes map for horizontal pipes.
kbaker |
to use outlet velocity in inlet
hi,
is ti possible to use this command in inlet where C_UDMI(c,t,2) is outlet velocity F_PROFILE(c,t,i) = C_UDMI(c,t,2); thanks in advance!!! |
Vague question lead to vague answer give some details about what you want to do.
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thanks for quick answer!
I am simulating gas-solid flow. So I want to save velocity and volume fraction in outlet and then to use it in inlet so I managed to save it with C_UDMI but in inlet everything is zero it seems it doesnt work. here is my inlet profile: DEFINE_PROFILE(abs_vel,t,i) { Domain *d; cell_t c, c0; face_t f; Thread *ct,*t0; begin_f_loop(f,t) { c0 = F_C0(f, t); t0 = THREAD_T0(t); if (C_UDMI(c0,t0,2) =0) F_PROFILE(f,t,i)=0.001; else F_PROFILE(f,t,i) = C_UDMI(c0,t0,2); } end_f_loop(f,t) } thanks for your help!!! |
help for inlet profile
Hi
is there anybody to help me? thanks in advance!! |
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You made a mistake, do I need to correct it. |
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yes,please... whrere is the mistake? I can not find it.. thanks for the answer! |
if (C_UDMI(c0,t0,2) =0)
this line: if (C_UDMI(c0,t0,2) ==0) |
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I did but it still doesnt work. it seems C_UDMI doesnt work for profile... I dont know why? Thanks again |
Hi,
There was another mistake, the value you stored was the UDM of outlet, but what you used was the UDM of inlet, so you never change (or store) the value into inlet. I have an idea, when you calculate the value of the outlet, you should get the thread (such as *tt) of inlet, if (((X_out - X_in)^2 + (Y_out - Y_in)^2) < 10^(-4)) F_UDMI(ff,tt,i) = value. hope it can help. |
Hi Kanarya
Another way you can follow is: (1) save the velocity profile in memory location (2) using DEFINE_ADJUST, employ this velocity profile on inlet Best wishes Mvee |
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with DEFINE_ADJUST,it seems working now but it gives inlet very small values comparison to outlet like(solid phase mass flow rate in inlet 1.3,outlet 227) but I don't understand why?:confused: do you have any idea? |
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thanks a lot for your help! I think it should work without value as well.. best!thanks again |
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DEFINE_PROFILE(solid_massflow, t, i) { cell_t c; face_t f; Thread *ct; begin_c_loop(c, t) { ct = t->t0; F_PROFILE(c,t,i) = C_UDMI(c,ct,0);} end_c_loop(c,t) } |
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DEFINE_PROFILE(solid_massflow, t, i) { cell_t c; face_t f; /* this format should not be changed*/ Thread *ct; begin_f_loop(f, t) /* this format should not be changed*/ { ct = t->t0; F_PROFILE(f,t,i) = ..... ;/* this format should not be changed*/ } end_f_loop(f,t) /* this format should not be changed*/ } |
Hi Kanarya
Please check by putting the monitor point that your inlet and exit velocities are similar or not? This is to ensure that your inlet velocities are updating at each iterations. Best wishes Mvee |
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yes they are updating but they are different(much smaller) than outlet. I do know why? thanks again! Best! |
Hi Kanarya
What is difference between the velocity at exit and inlet? Will it remain constant? - if yes then check UDF or inlet velocity remain small and constant irrespective of exit velocity - then you can not use Adjust function because this function might not be updating the inlet velocity at every iteration. Hence you will have to implement the updates in inlet velocity with some additional macros or loops. Best wishes Mvee |
people help me
Hi guys.
I am student . I want to simulate solid-Gas flow (two Phase) in Horizontal pipe by Fluent and in next step I want to make it and compare all result .It is very important for me. I try to simulate in fluent but unfortunately I couldn't. Could you please help me for design. ( please step by step or in a complete example ) Ex: 1- Define>model>multiphase 2-Define>... 3-... )!!! with best wishes Modheji |
I'm working on a horizontal air-water confined flow, and I got the slug flow. The problem is when the slug hits the upper part of the channel and blocks the air, this air must return as I think. But it doesn't. Do you have an explanation for this?
I'm sure that the air doesn't return because the air BC is velocity inlet, but I really want to understand where did the air goes once a slug blocks its passage to the outlet? I'll be grateful if you help me. Thanks |
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I'll be happy if you help me. I'm working on a horizontal air-water confined flow, and I got the slug flow. The problem is when the slug hits the upper part of the channel and blocks the air, this air must return as I think. But it doesn't. Do you have an explanation for this? I'm sure that the air doesn't return because the air BC is velocity inlet, but I really want to understand where did the air goes once a slug blocks its passage to the outlet? I'll be grateful if you help me. Thanks |
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