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CFDKareem
เข้าร่วมเมื่อ 15 พ.ย. 2022
The goal of this channel is to share my knowledge of complex CFD problems for everyone. Check out the videos for all things ANSYS.
Have a suggestion for a video? Send me a message or leave a comment!
-Kareem
Have a suggestion for a video? Send me a message or leave a comment!
-Kareem
ANSYS Fluent: Thermal Contact Resistance | Tips & Tricks
Improving the thermal contact resistance between two solids is critical in many industrial applications. To accurately model conduction between solid materials it is important that we count for this resistance in our models. This short tip shows you how thermal contact resistance is calculated and how to implement it into your models.
Note: This video was reuploaded. The original version contained incorrect units for thermal conductivity and thermal contact resistance.
Have a question related to Ansys Fluent? Have an idea for a future video? Leave a comment!
This video is for educational purposes only.
Note: This video was reuploaded. The original version contained incorrect units for thermal conductivity and thermal contact resistance.
Have a question related to Ansys Fluent? Have an idea for a future video? Leave a comment!
This video is for educational purposes only.
มุมมอง: 350
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ANSYS Fluent: External Flow Around Sphere | Tutorial
มุมมอง 220หลายเดือนก่อน
In this video we discuss the basics of external flow around objects. The flow around a sphere is analyzed and the drag and lift coefficients are calculated. Y Plus Calculator: www.cfd-online.com/Tools/yplus.php How to Perform a Mesh Refinement Study: th-cam.com/video/8PB_6h6m9vE/w-d-xo.html Video Content 0:00 - Problem Statement 2:40 - Spaceclaim Geometry 5:45 - Meshing 17:13 - Fluent 29:06 - R...
SpaceClaim Tutorial: A Beginners Guide to SpaceClaim DM
มุมมอง 2.2Kปีที่แล้ว
In this video we go through the basics of SpaceClaim DM. SpaceClaim is an incredibly powerful tool for cleaning and modifying geometries. It can be a bit difficult to get used to if you are coming from a features based CAD package. I hope this video gets you started! As always, please leave any questions or suggestions for future videos in the comments below! GrabCAD Valve: grabcad.com/library/...
Ansys Fluent: Introduction to Natural Convection | Tutorial
มุมมอง 4.8Kปีที่แล้ว
Natural convection is one of the most fundamental forces on earth. It keeps our seas churning, our sun burning, and our cell phones working. Natural convection is sometimes a challenging physics to solve in CFD. This video is a beginners look at modeling natural convection. Video Content 0:00 - Problem Statement 3:55 - Workbench Setup 4:17 - Spaceclaim Geometry 6:37 - Workbench Setup 2 6:55 - M...
ANSYS Fluent: Multiphase VOF Inkjet Droplet Generation | Tutorial
มุมมอง 6Kปีที่แล้ว
In this video we take our first look at multiphase simulation with the Volume of Fluid (VOF) method. This topic is just a brief introduction into the power of multiphase modeling. In future videos we will expand on this knowledge to perform ever more complex multiphase models. As always, please leave any questions in the comments! Video Content 0:00 - Problem Statement and Theory 6:55 - Workben...
ANSYS Fluent: How to Write/Read Boundary Profiles | Tips & Tricks
มุมมอง 10Kปีที่แล้ว
Utilizing profiles is a very powerful tool in ANSYS Fluent. Whether you are defining a inlet profile, variable wall flux, or almost any other custom boundary condition. Profiles also allow you to break up complex systems into smaller models to simplify systems level modeling. All without writing custom UDFs! Tutorial of backward facing step: th-cam.com/video/pWKNwuIgQt8/w-d-xo.html Have a quest...
ANSYS Fluent: Turbulent Backward Facing Step | Tutorial
มุมมอง 12Kปีที่แล้ว
In this video we take a first look at Turbulence modeling in ANSYS. The problem of flow over a backward facing step is a classic problem in fluid mechanics. This is a great model for getting started with understanding turbulence modeling from a practical standpoint. Experimental Data for Validation: turbmodels.larc.nasa.gov/backstep_val.html How to Create an Inlet Profile: th-cam.com/video/-42b...
ANSYS Fluent: Mesh Independence Study | Tutorial
มุมมอง 7Kปีที่แล้ว
Is my mesh good? Where are my simulation errors coming from? Creating a mesh for CFD can sometimes seem like a dark art. At the intersection of art and science is the mesh refinement study. This technique allows you to determine the optimal settings for your mesh prior to performing your simulation. If this video helps please like, share, and subscribe! Have a question related to Ansys Fluent? ...
ANSYS Fluent: Electronics Cooling Forced Convection | Tutorial
มุมมอง 29Kปีที่แล้ว
Here is a simple tutorial for setting up forced convection simulations in Ansys Fluent. This setup can easily be adapted to different geometries and different boundary conditions. Video Content 0:00 - Problem Statement 1:25 - Workbench Setup 1:58 - Spaceclaim Geometry 7:34 - Workbench Setup 2 7:55 - Meshing 15:35 - Workbench Setup 3 16:08 - Fluent 33:16 - Workbench Setup 4 33:38 - CFD Post 46:5...
SpaceClaim Tips & Tricks: External Flow Enclosure
มุมมอง 3.8Kปีที่แล้ว
Are you trying to set up an external flow problem in Ansys Fluent? This tip shows you how to quickly create the external flow domain for any object. Have a question related to Ansys Fluent? Leave a comment! This video is for educational purposes only.
SpaceClaim Tips & Tricks: Internal Flow Volume Extract
มุมมอง 10Kปีที่แล้ว
Are you trying to set up an internal flow problem in Ansys Fluent? This tip shows you how to quickly create the internal flow domain for a watertight geometry. Have a question related to Ansys Fluent? Leave a comment! This video is for educational purposes only.
hello karee, can you validate the results for this case?
Hello, this case was created solely for tutorial purposes and does not have any corresponding experimental data. Some estimations about the validity of the results can be gathered by solving analytical equations for the 1D heat transfer through the heated body.
hello kareem, Why when I add gravity the results does not change? how can I make sure that gravity is included in this case?
In the momentum equation gravity is added as a body force multiplied by the density. If you have constant density then this force is applied equally everywhere and therefore does not impact the flow. In other words, for forced convection in a pipe of constant density you will see no effect from gravity and it can therefore be neglected in the calculation.
@@cfdkareem Thanks for you respond. If I would like to have the gravity effect present even though my density is constant. Is it possible?
@abdullaal-tarmoom3437 yes, under general options you can check density and set the direction and magnitude. For earth gravity it will be -9.81 m/s^2 in the Y direction.
@@cfdkareem this is what i did for your case, I clicked on the gravity option and choose it to be -9.81 in the Y direction. The results stayed the same. So how can I make the gravity effect present in this case? much appreciated
@abdullaal-tarmoom3437 as stated before, you will see no effect from gravity unless you have variable density for the fluid material.
Thanl you I have a question regarding the definition of the fluid body In the properties tab there is an oprion (Fluid: False) Do I need to change it to true in order to define the body as a fluid domain in the upcoming processes? This option is locked and I can not change the (False) value, how to unlock it? Thank you very much
Hello Moustafa, you do not need to change this option in Space Claim. The final definition for the body will be done in Fluent and you can change between solid and fluid. In meshing you can also add a named selection to the body and give it a name such as "domain_fluid". This will tell Fluent that this is a fluid domain and will assign it correctly when the mesh is loaded. Again, not necessary since we can switch it in Fluent, but nice for workflow efficiency.
@@cfdkareem Thank you for your quick responce. I am waiting for your upcoming videos, you are doing a great job. 👍
Can you make a video of the circular pin fins in the rectangular channel for heat transfer? With Reynolds and Nusselt Number
can you help me download the crack version of ansysfluent , student version is not sufficient and not supporting my work, can you give a download link for the crack version please
Hello, unfortunately I cannot provide a version of Ansys other than the student license. What issues are you having with the student license that makes it insufficient for your model?
How could I apply this to a solder reflow simulation, with a 3d model? could you please help me. Thank you!!
Hey Josue, 3D VOF models are very computationally intensive so if you can reduce your model to a 2D axis symmetric or 2D planer it will be much simpler. I have a video coming out soon on the deposition and solidification of a metal droplet on a solid substrate. It may help give you some direction for your model!
sir, can we use shell conduction instead of using wall thickness to get the contact resistance??
Definitely! However, you will still have to provide a wall thickness and material for the calculation. Simple thermal contact resistance, shown in the video, models the layer as zero thickness which only allows heat conduction normal to the surface. Shell conduction will allow heat transfer both normal and planer to the wall. Shell conduction will also account for the additional thermal mass which can be useful if you have an interface layer of significant thickness.
@@cfdkareem thank you sir😊
Is ANSYS fluent free for students?
Yes! If you check out the short on my channel it shows you where to download it and some of the limitations of the student license. Let me know if you have any issues!
@@cfdkareem got it. Can you do a tutorial of a heat sink with a cooling fan in front of it?
I have a tutorial on my channel for forced convection through a heat sink which will give you the basics for this problem. Are you trying to model the fan explicitly?
@@cfdkareemmodel fan explicitly
@kaleb101 ok great! I'll add it to my list for future videos.
This is awesome
Thanks!
Thanks!
Thanks!
Thanks!
Hi! Great video. I noticed the parameters you read into fluent did not have dimensions. Are they in metric? If you change the units in the fluent menu to English units, but you read/import those profiles let's say in SI units, what happens? Is the profile data always have to in SI units ?
All profiles must be in SI units. Fluent always operates under the hood in SI. When you change to English in the GUI it's doing a "visual conversation" well still using SI under the hood.
Very nice introduction thank you!
Deserves way more views forgot to add!
Glad you liked it!
I have problem i want to fill this geometry with fluid ,i try your vedio but i have problem in velocity contour is empty don't fill with fluide
Hello, are you trying to change the flow from air to water? Or trying to do a multiphase simulation with air and water?
hi great video, how would you recommed approaching the same problem with water instead of air, and making it a multiphase problem where some of the water boils off, i am currently trying to do this but i cant seem to achieve convergence of the fluxes [energy]
Boiling is a fairly complex simulation which will require multiphase and the boiling/condensation model. Is this what you are trying?
Thanks for such a great tutorial. Firstly, Would you please let me know how you got the pressure inlet profile? In my case actually, I have a voltage pulse profile, but I am not sure how to convert it from voltage to pressure profile. Any methods to find this pressure profile. Secondly, I couldn't find the geometry details that you have used for this tutorial, would you provide it in a detailed manner like nozzle inlet dia, throat dia along with the air chamber width.
Hello, going from voltage to pressure requires an initial simulation that models the piezo movement. I obtained this profile from such a simulation. To model this you will have to model the whole ink chamber. You can do this with a single phase simulation and have a pressure=0 condition at the outlet. You will then input the voltage profile to drive the motion of the piezo and export the pressure generated right above the nozzle. I will add such a model to my future video list!
Wonderful tutorial. What a life saver mate.
Glad it helped!
thamks a lot
The video was very clear and helpfull. Thanks.
Glad it was helpful!
Dear Kareem, I would like to know what the analytical equation is for the velocity profile. Thank you.
There are numerous equations for estimating the turbulent velocity profile. The most common for industrial flows is known as the Prandtl one seventh power law which takes the form: u/Umax=(y/R)^1/7. You can plug in Umax and R to solve for u over the range of y.
hello sir, im trying to simulate a similar case but with small inlet lenght to see the vorticies at the top wall. However, nomatter which methods or solvers i use i can not get the same results with published articles."E. Ertürk, Numerical solutions of 2-D steady incompressible flow over a backward-facing step, Part I: High Reynolds number solutions, Computers & Fluids 37 (2008) ". Can you give me any hints to handle this simulation. Laminar case is easy but i can only get top vorticies with DES method but it is still not accurate. I can not get the 3third vortex for Re = 3000 and the other x/h values doesnt match with the reference.
Our teacher said u can use k-epsilon for turbulence but with that method you can only get the first vortex others only appears for the initial iterations then dissappear.
also, with very fine mesh (i have uniform 150k grids) DES methods takes almost 2k iterations to hit 10^-3 criteria and oscillations never stops as i see.
Hii, could you please design a prismatic Li-ion battery pack of 4P23S in SolidWorks/Ansys with mechanical support?
Hello! Thank you for the amazing tutorial. Can you please share how you created the pressure profile? I am want to create a pressure profile from some input parameters (for a piezo inkjet nozzle). It would be great if you can refer me to some existing work that discusses more about this relation
Hello, the pressure profile is in the video description!
I used that pressure profile, I wanted to know how was that generated? Do you have any reference literature so that I can modify that pressure profile according to my operating conditions. Thank you!
@AdityaChivate this pressure profile is just an arbitrary waveform for the purpose of the tutorial unfortunately. If you look through some literature on inkjet waveform generation you may be able to copy a representative one from the literature.
@@cfdkareem Thanks for your reply. I'll check around to see if there's any existing literature that talks about this.
Hello sir, thanks for this nice tutorial. Can you please provide us with the geometry details ?
yes a 3D Model would be great. I addition a cooler on the enclosure with forced convection would be a great add on. Is it possible to take the surface temperture of the enclosure as an heat surce of a new thermal calculation? How would I do so? I general it would be great, if you show how to connect different thermal analysis (or a thermal analysis with an fluent analysis)!
Hi, I can’t seem to find where to download the experimental data, and the link I’m pressing only opens up a new tab with the data
Hello Joaquin, near the bottom of the NASA page there are two links to the Cf and Cp data. Clicking the links will open a new tab with the data displayed in text format. You can then copy the data and paste it into excel or a text document.
Infinitely better than any of the Ansys provided "courses" on youtube.
@cfdkareem...I want to calculate the thermal and viscous entropy. Please guide how to find that data? I found the entropy in the volume-avg option by selecting Temp. But I don't know how to calculate thermal and viscous entropy. Thanks
Hello, in this case, with such a low Reynolds number, the viscous heating was assumed negligible. If you want to calculate viscous entropy you will have to turn that option on under viscous models > Laminar > Viscous heating, and recalculate.
@@cfdkareem Yes, I found the viscous heating option in viscous model. I found the following statement: Viscous Heating (if enabled) includes the viscous dissipation terms in the energy equation. This option is recommended when you are solving a compressible flow. Note that this option is always turned on when one of the density-based solvers is used; you will not be able to turn it off. In my case, my flow is laminar and incompressible. I am using pressure-based solver as well. In that case, how can I calculate "Viscous entropy" and Thermal Entropy"? Looking forward to your kind response. Thanking you.
Very informative....👌
Hi Kareem, when you calculated the wall distance why did you put 0.01 as the boundary length and also, why is the wall distance you calculated on the website different to the one you put into Ansys. Thank You.
Hello, the characteristic length used to calculate the Y+ is the step height, 0.01 m. Good catch on the wall distance! The one calculated on the website should have been used as the first layer height of the inflation. It looks like I forgot to paste the value!
@@cfdkareemyh that was really baffling me, but thanks for clarifying
@@abhishekbenny7930 even I noticed both things. for the second point, i felt as if kareem has rounded off the value 5.2x 10-6 to 1x10-5. Though I could not understand as to why the reynolds number value appearing on the Y+ calculator did not matched to 36,000 as stated at the start of the problem. Can you advise pls. Thanks
Hello, Could you please describe in a short video how to do the same cooling study but in large scale for data Center hall containing many racks and servers
Hey Ahmed, if you're modeling a datacenter HVAC system you often build up a series of simulations, instead of modeling each individual heat sink in each server. It starts my modeling a single server and calculating the total heat output of each server. You can then estimate the total heat output of all the servers in a rack. Each rack will be modeled as a fan boundary condition with a specific pressure jump and temperature jump. These racks are modeled inside the larger data center and the HVAC system in the room is analyzed. If this is what you are interested in I can add it to my list of future videos!
Hi Kareem, please I’m having issues with the secondary simulation can you share the file of the velocity profile?
Hey James, I've added the inlet velocity profile to the video description! Copy it to a .txt file. It can then be read in as a profile for the velocity inlet.
Hello Mr. Kareem. It’s not clear to me about how you created the velocity profile. did you start from space-claim, and create new geometry and meshing? you just switched to a new video, was it same goemtry as before? can you please explain the background process, some of us are beginner-level. Or is there other ways I can modify the inlet in the primary simulation to get a fully developed flow, I’m not getting this pattern. I tried to create a rectangle of 3900mm and 100mm dimensions and during the meshing it was very slow and frustrating
Hello James, yes the second simulation is created using a full new model including geometry in SpaceClaim, meshing, and a new fluent setup. The second simulation is simply a 2D rectangle with a height equal to the inlet height of the primary simulation (turbulent step). Make sure you are not using a very small mesh size for this simulation. The mesh will still be fairly large, but shouldn't take more than a few minutes to create. You can also do what you mentioned, i.e. extend the inlet of the turbulent step simulation far enough to allow the flow time to become fully developed. The benefit of splitting the simulation is that your primary simulation, the turbulent step, will have a much smaller mesh size and therefore a faster calculation time.
Best video❤thank you
Hi Kareem, when simulating the flow through the pipe to get velocity values before the backwards step, through looking at the contours it doesn’t seem like its flowing properly as all i can see is blue at the inlet, then there is a small red vertex in the middle and then the flow in the pipe goes blue. Do you know why this might be?
If you have one vertex much higher than the rest of the flow it is usually one of two problems. Most likely there is a bad mesh element that is not converging well. Try remeshing and possibly refining it to see if it improves. The other potential is that the simulation is not fully converged. Try running the simulation for more iterations and see if it converges. If neither of these help them check your boundary conditions and make sure the inlet velocity/material properties are set correctly. Let me know how it works out!
@@cfdkareem I’ll give this a try - thank you for fast response :)
for three day, with bugs and errors, but in the end it worked
Great to hear! Could you describe your bugs/solutions you faced? I'll make sure to cover them in future videos.
After doing as you just described, I want to add a rectangular region to my mesh to achieve denser meshing for fluid flow. How can I do that? Thanks.
You can use the sketch feature and select a face you want to sketch on. You can then use the rectangle tool and pull tool to create another rectangular body. You can then use this as a body of influence in meshing to refine the region.
@@cfdkareem Thanks. I'll try it.
I'm trying to find the boundary layer thickness value at that line, is it by inserting a chart of variable x velocity and y y axis, i need to match the B.L thickness value with what I have before exporting the profile
Yes you'll want to create a line extending from the wall and plot the x-direction velocity vs y. You can then find the height where the velocity along the wall achieves 99% the free stream velocity.
@@cfdkareem Thank you, and in terms of mesh independence, how should that carried out as we have two separate domains, I mean if my parameter is the reattachment length how would I refine the first domain to export the profile then refine the second one !
Great question! In the first domain your output is the developed velocity profile. This can be calculated analytically so you could compare your simulated profile to the equation. Reducing error in the profile will give the most accurate results for the reattachment. You can then use the profile in the second and analyze the mesh sensitivity for the reattachment point. However, mesh independence mostly comes down to how much accuracy you need from the model. For me personally, in an industrial setting, I would use my engineering judgement for the first mesh, confirm the profile is acceptable, and then perform an analysis on the second, since I'm mostly interested in the reattachment and can tolerate a small amount of error. As with most modeling it's all about using your judgement, experience, and skill to determine the best way to get the information you need!
Hi, can I just extend the upstream length for this case instead of creating a secondary simulation for inlet profile ? will that works the same
It will! You just have to make sure you extend it far enough for the flow to fully develop. It will also increase your solving time as the mesh will get much larger.
Thanks for the video
Isnot it better and quicker than creating a box, then subtracting the aerofil etc to get the empty solid region walls>?
That works as well! If you have a multi-body model then the enclosure tool is more useful. For simple geometries it's just about as fast as the subtraction method!
Hi CFDKareem, it is a nice tutorial and pretty interesting. Let me ask you a question, in your case, was the mesh of the first simulation equal the second simulation in the points of the profile? If the mesh of the first simulation was twice the size the second simulation you would need to click in the interpolation option, right? Another question is if you know if is possible to write expression in the boundary accordingly with a new coordinate and now global coordinate.
Yes, the two meshes are identical. I would try to maintain consistent meshes when possible, but if you can't the interpolation works well. From my knowledge, Fluent always references the global coordinate system for profiles and UDFs. You will have to manually translate your input profile in reference to the global coordinate system. If you know where the profile is going to be implemented, I try and move the geometry to an ideal location in Spaceclaim to make writing the profile more convenient. For example, if I am writing an inlet profile I will put the bottom of the inlet right at the global coordinate system so the bottom edge starts at 0,0,0.
@@cfdkareem kareem, I really appreciate your answer, thank you. If you don't mind, I would like to ask you another question about DOF in fluent. In case you know the answer, the question is: I would like to now if it's possible to set magnet field in DOF of fluent to interact with magnetic wall. This magnetic field is responsible for rotate a rotor that is set as wall in fluent. The flow of fluid is responsible for increase the rotation and temperature of this wall. Also, the magnetic properties of the wall material change accordingly with the its temperature. So, at first, the inputs of my model are the inlet velocity and temperature, outlet pressure of the flow and the magnetic field that is interacting with the wall which generates rotates. Do you know if it's possible to simulate this in fluent?
@Rau379 it's definitely quite a complex problem! It would be difficult to do through the graphical user interface, but can likely be done with a UDF. The wall motion and properties can be defined using the macros DEFINE_MOTION and DEFINE_PROPERTY. There is no defined macro for defining magnetic fields that would interact with a solid boundary. You will likely have to create a custom function for the wall motion and define it under the motion macro. Check out the Fluent customization manual for more info on UDFs.
Hi Kareem, Thansk for the explanation. It was very helpful. In my case I have more than 50 mm long straight tube, then a tapered (45 degree) section then 2mm long another straight section then the lquid introduced to multiphase system. Where do you think I should cut my nozzle region (before taper after long tube region, after taper and before last straight section or just before the nozzle exit and introduce profile to main simulation) so that I could lower my multiphase calculation time.
Ideally wherever you can cut the domain that would reduce mesh size and you can confidently assume the boundary condition at the point. You could also do a preliminary run with a single phase, and then export the profile right before the nozzle. It all comes down to your own engineering intuition on what will effectively capture your problem.
@@cfdkareem ok thanks a lot. I wasn't sure if I cut whole secondary phase injection (nozzle) and put that velecity profile as b.c. into a meshed face at the bottom of my test section it would simulate exactly the same condition. Like at the first time step would it model the liquid just like the real case(if I cut the whole scondary phase/nozzle) or should I provide some of the last section (after the taper) of the nozzle exit in to my whole simulation. But if the only important parameter is to reduce the computation time then it would be wise to divide it from nozzle exit and introduce whole nozzle exit velocity profile as b.c. to face mesh of nozzle exit. Thanks a lot