ANSYS Fluent Tutorial : Drag and Lift Calculations in ANSYS Fluent (Part-1)

In this tutorial, it has been shown how you can calculate drag and lift forces and coefficients. A rectangular plate has been taken as a specimen and placed perpendicular to flow direction. The air at high velocity is blowing over it. Due to blow of air, the drag and lift forces got developed on this specimen. In the current tutorial, it has been shown how you can calculate the drag and lift forces.
What will you learn from this tutorial?
Creating the flow domain in ANSYS Design modeler
Structured Mesh Creation
Solver setup
Drag and Lift calculations
CFD post Processing
This is Part 1 of the Tutorial.

[@adamrozman]

Sorry, started crying profusely with the first song. I can't see much of my screen through the tears but I'm sure my lift and drag calculations are great 👍

[@AnsysTutor]

😀😀😀. Sorry that that.

[@RS-qe7mj]

Hi, you should use boolen to subtract the wall out of the fluid so that you can get continuity of the meshing, otherwise the nodes in the mesh at the contact region would not have same continuous nodes.

[@AnsysTutor]

Watch the geometry creation part. The enclosure behaves like the same way as the Boolean substract.

[@kingstonmichaelson3609]

Thanks for the content. Really helped my assignment

[@AnsysTutor]

You are most welcome.

[@relaxgaming29]

May I know why the settings in reference value is not edited? Since area, length are different based on the geometry

[@badrulamin6919]

Thanks for the nice video...Sorry I want to ask why some of the Cd value is very high which is up to 500 or is it normal? Sorry if my question sounds stupid...I don't have much knowledge about aerodynamics

[@yayanm1k689]

Thanks for detailed video. Although I had rather different result for 20:52...

[@AnsysTutor]

Results differs due to the different meashing.

[@Nimzie458202]

Hey, my Drag and Lift graphs are no longer showing any movement and when I click compute I’m now getting incredibly smaller numbers. I did absolutely everything identical but I don’t know what is happening!! Was working before but now for some reason it’s not working anymore?

[@hongywei2773]

I like your tutorials. Thank you for your posts.

[@AnsysTutor]

Most welcome,😊😊😊

[@berkanyuksel1997]

I just wanna say Thank You:)Nice tuto.

[@AnsysTutor]

Most welcome :)

[@ДанилЮсупов-п5п]

Thank you. You make a great job!

[@AnsysTutor]

Most welcome , its all your love for our channel.

[@張香閏]

sorry for poor English. After I run the calculation and it show a window says calculation complete, there is nothing change in workbench. the setup and solution did not change to check. nothing came to the result window. what can I do for this situation?

[@AnsysTutor]

You should right click on solution and select update.

[@張香閏]

@@AnsysTutor It doesn't work. I've try to update both setup and solution but nothing change.

[@張香閏]

I find a weird way to avoid this is to load the data manually into CFD-post. It seems work

[@danielrajkumar7075]

I have Ansys version 16.0 . How do i go with the report definition part, as my version has not got that function.

[@mohammadaziemkhalid8264]

Hi, can i follow this step to calculate wigcraft lift and drag?

[@ziadalkasem8380]

Thanks for this useful video. I am doing a simulation for drag force calculations of a high powered model rocket and I was wondering if i could use the same steps for the calculations. Plus, does the mesh have to be structured in my case? and am i also supposed to mesh the rocket instead of just boolean subtracting it?

[@renrenflores8574]

I notice in your boundary conditions another boundary was added and it was not originally there. Maybe thats the reason my lift coefficient plot doesnt make any movement.

[@AnsysTutor]

Some of the Boundaries are generated by solver itself apart from the named selections. To know about these boundaries ,you should select the highlight option turned on.

[@basarbadalioglu7800]

Hello sir,i am calculating the Drag force,lifting force and Cd as well for my submarine flowing in the water.This video helped me a lot thank you for this.but the problem is this is in the air,how can i simulate the samething in the water?Which values do i have to change and where?Thank you!!!

[@AnsysTutor]

You need to change the material properties only.

[@basarbadalioglu7800]

@@AnsysTutor Thank you,preciated!

[@faizanakhtar9086]

Background music is awesome.

[@AnsysTutor]

Thank you.

[@severnsevern1445]

Great video! Please How to compute/calculate the standard deviation of the aerodynamic forces coefficients using fluent? Thank you in advance.

[@makavelli9705]

Hi so im doing a potential flow simulation on a nonsymetric object. This means lift amd drag must be =0. But im getting negative values. Any help? Flow is steady inviscid irrotational and incompredsible

[@AnsysTutor]

Check the direction vector.

[@makavelli9705]

@@AnsysTutor the direction vectors are correct. Is it possible because ansys only computes the force along the direction vector not the sum? If it computes sum of forces on this vector it should be =0. I.e the y axis output =2KN and the weight=-2KN

[@curdlegon]

How can we calculate drag on the walls of a porous body which are set as interface in fluent?

[@AnsysTutor]

Sorry ,dont have knowledge regarding that.

[@thetei6945]

At the end of this tutorial, there're 3 tab bars: Scaled residual, drag and lift but you get pathlines coloured by veolcity magnitude just by clicking lift coefficient tab bar. I'm confused in that part. Can you explain me please. Also I can't close fluent.

[@AnsysTutor]

I have not shown the pathlines, it might be the plots only, please check once again.

[@thetei6945]

@@AnsysTutor Thanks for your reply! I'll check and try it again.

[@thetei6945]

I've got it right Sir. Thanks for your tutorial videos !

[@NihalRanjanM22ME062]

can dynamic mesh is possible for this simulation with udf

[@AnsysTutor]

Yes possible.

[@NihalRanjanM22ME062]

@@AnsysTutor can you give some tips regarding dynamic mesh how to add it for this case

[@LarKanon]

I'm trying to figure out which geometry has the least Cd, but I'm always getting 0, everything else seems normal, any ideas what could it be? It seems to be a mesh problem... why is the mesh not surface only?

[@AnsysTutor]

Check the force vector direction.

[@baraandre3731]

Sorry sir, I'm in project to design aerodyamics body and I got the value of Cd but nonsense I think so. Some of my friends told me to evaluate area considered as projected area in the "reference values" (as we know, fluent basically give unity value as the default number for area). Then, when I tried to change the value of area in "reference values", suddenly I got the proper value of Cd and I don't see it why this things can happen. Or is it necessary to change the default value of area? Thanks in advance

[@muhamadfudhail99]

good tutorial...can I imported .iges files instead of a box and follow steps in ur videos?

[@AnsysTutor]

Yes. Be careful with the force vector direction.

[@muhamadfudhail99]

@@AnsysTutor hi..can u show how to compile udf function into ansys fluent?

[@Mo.w77]

Thanks for your useful tutorials... Do you have an idea how to calculate a drag on an interior surface (say a droplet) ? I tried integrating the velocity gradients over the area and multiply by the viscosity (through CFD-Post)but it doesn’t seem to work

[@yasirqazi2853]

why is it showing drag and not Cd in my results even though i selected drag coefficient in report definition?

[@AnsysTutor]

Check which window have you selected for that display.

[@mustafaerguvan3604]

Perfect tutorials 👍

[@AnsysTutor]

Thank you:)))

[@mehmetbayezit1883]

Perfect

[@AnsysTutor]

Thank you

[@harismunir720]

Hello Can i apply this on RC plane model and find lift ,drag cofficient?

[@AnsysTutor]

Yes.

[@shahshah6641]

Hi sir.. Can i select all force vectors in xyz direction to calculate drag force? I know for lift only y direction but for dragforce can i set all xyz direction because i want to calculate the drage for quadcopter flow?

[@azooz05030]

Can calculate lift force for boat in same way?

[@AnsysTutor]

Yes.

[@erickrobles6365]

Question: Why do you select "Wall-Solid" to calculate drag coefficient and lift coefficient instead of selecting the body you are analyzing the flow of air over? In this case, the flat plate which is named "Adjacent Walls"? I always used the latter and would get really high drag coefficients and I see it wasn't the right way. Thanks!

[@AnsysTutor]

Drag force can be found out on the total body, not on the face as, we are putting the force vector direction in z- direction, so you can't get a accurate result for the face as the back side of that face might be a solid one . If it's a 2d surface you can analyse using the face, but in 3d geometry you need to select the body.

[@erickrobles6365]

@@AnsysTutor Right, I understand that we want the drag on the entire body. But i see that a "named selection" as created on the entire body of the flat plate (adjecent walls). So techncially, since you created a named selection for the entire body, why wasn't the body (which in this case is named adjacent walls) selected? I realized that the "wall-solid" bounday condition option only appears when symmetry is not being used. So how would the selection bc different for the symmetry case forna 3d case? Thank you!!

[@AnsysTutor]

@@erickrobles6365 as you can see the named selection is not for the entire body, the adjacent walls are the 5 faces of the flat plate ,and one side (the front one is named separately), so drag force can't be on only the 5 faces as you are saying, we need all the 6 faces. there is a mistake in named selection, I should have done the named selection for all the 6 faces as one as you are saying, but the reason behind the separate named selection is that I want to see the result of drag forces in front and back faces separately but it didn't give any satisfactory result so, I had ommited that part from the tutorial.

[@erickrobles6365]

@@AnsysTutor oh! That makes sense. I didn't realize that you had ommitted one of the faces. Thank you for the quick response! I'll be sure to keep this in mind when I conduct future fluent studies

[@azooz05030]

Hi I want calculate drag force Is it the same way?

[@AnsysTutor]

Yes.

[@azooz05030]

@@AnsysTutor Thanks bro

[@jsr5816]

This may be a really stupid question...but when you print the lift and drag force vectors to the screen and the units for the force are "n" (specifically a lower case n) is that Newtons or is a specific form of Newtons like per unit area or length? I'm currently designing the aero package for a Formula Student race car at the moment so it is a rather critical point! Great video :D

[@AnsysTutor]

its newton, generally in fluent you can check the units and its symbol at the top left corner-> units.

[@apparaosurada9928]

How to fill reference values for engine geometry to calculate drag force on it i mean area etc..

[@AnsysTutor]

You have to select the face which you want to observe the drag force, name it using named selections in meshing, and in setup you can acess this named boundary to observe the drag force.

[@Mahmud2hasan]

how would this be done to calculate the pressure drag and the skin friction drag separately?

[@arifaziz4030]

In the definition report, I only have drag force. I dont have any option for drag coeff. May you help me

[@AnsysTutor]

Which version software are you using

[@arifaziz4030]

@@AnsysTutor Ansys 17

[@wongyithong9838]

How long does your calculation takes? In 1000 iterations

[@AnsysTutor]

It depends on the problem and the model. If its a 2D model then the problem will take less time.

[@nyx3745]

Quick question, I am learning this to perform a simple calculation for a forward swept airfoil design, can i follow these same steps exactly or are there any modifications to do?

[@AnsysTutor]

Yes you can follow these steps, remember to validate the result with some standard journal research papers.

[@nyx3745]

@@AnsysTutor Yup thanks

[@AnsysTutor]

Most welcome🙂🙂🙂

[@henrycoldrain8151]

Hey. When i try to report my Cl and Cd i get values like 1.3209450 e^-28 instead of your values. I believe I followed your tutorial perfectly. What could be the reason of this

[@henrycoldrain8151]

excuse me i just had to run the calculation i thought initialaziton wouldb e enoughh my bad. But i get negative values instead of positive. I guess ı made an error in directions

[@AnsysTutor]

Check the force vector direction.

[@firdausghani8424]

I'm meshing a UAV model, got many errors after i setup for body sizing. Can you help me?

[@AnsysTutor]

What are the errors.

[@PrakashGupta-ux9jf]

Sir, i want to put Parabolic velocity profile at inlet, here u taken an absolute value of velocity. I dont know how to write C Program. Is there any other way to define those velocity

[@AnsysTutor]

you can modify your geometry so there would be a flow developing region, and the part where you want the parabolic velocity you can get that. otherwise search for the parabolic profile UDF in fluent udf manual.

[@Nayebe]

Why does the chart come out constant when I get the x and y values zero?

[@AnsysTutor]

check the coordinate of the X,y=0 ,the geometry might not be at that point . check the geometry and get the point where it lies according to that find the graph.

[@PrakashGupta-ux9jf]

sir plz upload part 2

[@anuragraikwar6705]

I think if u dictate steps then it is more understandable.. 👍

[@AnsysTutor]

thank you , will try to.

[@micheleguardiani2596]

sei un boss

[@AnsysTutor]

Thanks .🙏

[@lm1890owpke]

Hey man thanks for this. But when I set the iterations to 1000 the plot only shows the result up ti at 180, no matter what number I change iterations to it still stays at 180. What should i do

[@AnsysTutor]

it might be showing solution is converged at 180 iterations, that means you dont need to run the simulation more , as the numerical result is good enough to proceed.

[@AnsysTutor]

but if you still want to run the simulation for more no of iterations then decrease the residual value.

[@yayanm1k689]

You may check "Solution control" 15:37, it works for me.