how can i calculate pressure drop in a pipe ( in fluent ) and compare it to thee theoratical value

Hi

Go to: Report--> Surface integrals--> Report type (Area weighted Average)--> Field variable (Pressure, either static, dynamic or total). Choose the inlet and outlet from the list and find the difference to get the pressure drop.

Regards

AAA

pressure drop can be found out in fluent by looking at the values of total pressure at the required surface and findin the difeerence of it. in fluent go to SURFACE INTERGRALS in REPORT and select the area weighted average ... select tghe surfaces .sa apply ...see the pressure ... dont confuse with net... subtract yhe higher and lower ll give drop....

[hadial]

I have a periodic bc , how can I calculate it using that bc ? can anyone help me please?

[vasava]

You can see it in the periodic condition setup.

[hadial]

thank you for your prompt response, but what I see in periodic condition is pressure gradient , not pressure drop, sorry if my question seems really easy one, but I am totally confused

[LuckyTran]

Originally Posted by hadial

thank you for your prompt response, but what I see in periodic condition is pressure gradient , not pressure drop, sorry if my question seems really easy one, but I am totally confused

Just multiply by the period (the streamwise periodic length).

[hadial]

Originally Posted by LuckyTran

Just multiply by the period (the streamwise periodic length).

Thank you luckyTran U r undoubtedly one of the bests here

[shiva krishna]

Hello, i have read your text that you have answered few years ago about pressure drop, by reading your answers i thought you are the correct person to answer my question , i have a doubt in regarding the pressure drop. Which pressure values should i take while calculating the pressure drop? In my case i have taken inlet has atmospheric conditions (pressure- inlet) and outlet is known value i.e. i have taken target mass flow rate (pressure -outlet). Now i want to calculate the pressure drop i.e. difference in pressure at the outlet surface to atmospheric pressure. Is this correct way to calculate? Moreover I am taking take static pressure at outlet surface , for your understanding i am using Ansys Fluent.

[Maddin]

Funny how many discussions are opened for pressure drop.
1. which report type is valid? some mention sum, sum integral, some area averaged, some mass averaged... expression "report1 - report2"
2. which pressure is valid? total pressure, gauge pressure etc. pp.

I use total pressure, the zone report isn't so important when you always use the same type to compare... area averaged, mass averaged what ever...

I could image that at Ansys you have a group of 2-3 guys which are always thinking about nice features to make the software more "sophisticated" - so without 2-3 months of teaching you even can't calculate "stress less" without googling 2-3h the pressure drop

Same for ramping boundary conditions... hehehehe

Yes, I'm joking cause it's a mess... and it's saturday evening... cheers

[esha]

Hello, I have set inlet boundary as translational periodic, I do not have any outlet. How can I calculate pressure gradient? Or if I am not wrong in understanding from above discussion should I just select inlet and check pressure and then multiply by its translational periodic length? If not, please let me know. Thank you!

[LuckyTran]

Originally Posted by esha

Hello, I have set inlet boundary as translational periodic, I do not have any outlet. How can I calculate pressure gradient? Or if I am not wrong in understanding from above discussion should I just select inlet and check pressure and then multiply by its translational periodic length? If not, please let me know. Thank you!

You can't set only an inlet as periodic, you have to set it to a pair of boundaries.


If you used the periodic boundary conditions the pressure gradient is part of the periodic conditions.


If you want the pressure drop, then you multiply this pressure gradient by the length.


If you are not using periodic boundary conditions then there's many non-trivial ways of getting "pressure drop" between two thingies.

[esha]

Originally Posted by LuckyTran

You can't set only an inlet as periodic, you have to set it to a pair of boundaries.


If you used the periodic boundary conditions the pressure gradient is part of the periodic conditions.


If you want the pressure drop, then you multiply this pressure gradient by the length.


If you are not using periodic boundary conditions then there's many non-trivial ways of getting "pressure drop" between two thingies.

Yes, I have set as a pair and used x-momentum source term for flow. may be it is very easy to find pressure drop but I am just confused. So can you elaborate please?

[LuckyTran]

Originally Posted by esha

Yes, I have set as a pair and used x-momentum source term for flow. may be it is very easy to find pressure drop but I am just confused. So can you elaborate please?

Well you are confusing me.

If you used a periodic pair then in the periodic conditions, the pressure gradient is a user input. If you use targeted mass flow rate, then it spits out the pressure gradient back at you. A hint: at one point you should have used /define/boundary-conditions/modify-zones/make-periodic

If you never typed in this command then you've done something wrong.

The pressure gradient is the momentum source... I have no idea why you would add a momentum source on top of the pressure gradient... But supposing that you did, it sounds like you already know what the answer you are looking for? How about you elaborate on what it is you've actually done? You didn't mention anything about a momentum source before. Next you will tell us you are actually using a program other than Fluent?

[saimazainab]

Originally Posted by LuckyTran

You can't set only an inlet as periodic, you have to set it to a pair of boundaries.


If you used the periodic boundary conditions the pressure gradient is part of the periodic conditions.


If you want the pressure drop, then you multiply this pressure gradient by the length.


If you are not using periodic boundary conditions then there's many non-trivial ways of getting "pressure drop" between two thingies.

It may be seems very late to add something on this topic
But i am stuck and want to to how to maintain known pressure difference between inlet and outlet

[Harishkolla]

Hello all,

I have a pipe with an inlet pressure of 30 bar and at the end of the pipe is connected to other geometry (not open to atmosphere). I need to find the availability of pressure at the end of the pipe.

How to calculate this I new to fluent