WEBVTT 00:00.200 --> 00:01.010 Hello everyone. 00:01.010 --> 00:04.730 Welcome back to the CFD using Openfoam beginner to intermediate course. 00:04.730 --> 00:06.830 So this is our class nine. 00:07.670 --> 00:12.560 Uh, in this class we'll be seeing automation with Aldrin file and all clean file. 00:13.520 --> 00:16.520 So automation with Aldrin file works like this. 00:16.730 --> 00:23.360 If you have the set of commands like running block mesh decomposing and then running it in parallel, 00:23.360 --> 00:26.360 those commands has to be entered manually in terminal as of now. 00:26.360 --> 00:31.070 But if you want to make it automated then you can use the old file to do this. 00:31.220 --> 00:34.820 The purpose is streamlined execution of Openfoam simulations. 00:34.850 --> 00:39.950 Benefit is it automates the entire simulation workflow by reducing the manual steps. 00:40.160 --> 00:43.280 After initiating the alternate file, you don't have to do anything. 00:43.280 --> 00:45.140 It just finishes the entire simulation. 00:45.140 --> 00:48.560 And then you can interact with the computer just to post-process. 00:49.460 --> 00:55.180 So to create an alternate file, generally the components are like mesh generation, initial condition 00:55.180 --> 01:00.490 setup, solver execution, and call for post-processing like force plotting and all. 01:00.550 --> 01:01.960 Not the paraview thing. 01:01.960 --> 01:07.030 So the structure would be it is a shell script that sequentially runs necessary commands. 01:07.030 --> 01:10.450 So that is all that uh, and all run file is. 01:11.170 --> 01:13.900 So we are we have an example here. 01:13.900 --> 01:17.200 So you can open all file in any text editor. 01:17.200 --> 01:18.100 And you can see it. 01:18.100 --> 01:24.190 And the command to initiate alternate file through WSL is bash uh space dot slash Aldrin. 01:24.400 --> 01:28.750 But if you're on ubuntu it is just dot slash Aldrin. 01:29.140 --> 01:31.960 So you can see that it has a header. 01:31.960 --> 01:37.390 It says uh dollar w rm project directory bin slash tool slash run function. 01:37.390 --> 01:38.410 So that is essential. 01:38.410 --> 01:39.340 That is like header. 01:40.450 --> 01:45.810 If you want to clean old case files then the command would look something like run application. 01:45.810 --> 01:50.250 Run application is the shell script command to call the application kind. 01:50.250 --> 01:52.980 So it is rm minus RF. 01:52.980 --> 01:56.190 It delete deletes the polymesh under constant. 01:56.280 --> 02:05.520 So it points to the uh program that it has to delete any file that starts with 0 to 9 any number. 02:05.520 --> 02:07.300 So that is one method. 02:07.420 --> 02:10.960 And to generate mesh we will be running the application block mesh. 02:10.960 --> 02:16.540 If you want to set up the initial condition by decomposing then it is decomposed power. 02:16.690 --> 02:19.150 And the hyphen force is generally not used. 02:19.150 --> 02:20.320 But it is a. 02:21.400 --> 02:24.130 It is just an example from an alternate file. 02:24.280 --> 02:26.890 So you don't have to worry about the force. 02:26.890 --> 02:29.290 You can stick to whatever we have learned in this course. 02:30.010 --> 02:35.550 Then when you want to run solver in parallel, you use the command run parallel and simple form space 02:35.550 --> 02:39.450 hyphen parallel so you don't have to write MPI, run and be a parallel. 02:39.480 --> 02:43.170 All these things are not needed so it will do it for you. 02:43.170 --> 02:49.410 Just have to mention the number of processors somewhere and for run application we can uh do reconstruct 02:49.410 --> 02:52.650 part also and post process function like forces. 02:52.650 --> 02:56.870 So we can do all of these and benefits of order and file. 02:56.870 --> 03:00.800 It ensures that all steps are executed correctly in the right format. 03:00.800 --> 03:06.770 When we are working with terminal, we are bound to make mistakes sometimes in the working directory 03:06.770 --> 03:13.070 or while typing the commands, and we might be wondering what caused the issue so these things might 03:13.070 --> 03:13.700 happen. 03:13.700 --> 03:17.840 To prevent those things, we can use order and file the efficiency. 03:17.840 --> 03:23.210 It saves time by automating repetitive, repetitive tasks like you are running block as you're waiting 03:23.210 --> 03:25.400 for some time, or initiating the solver. 03:25.430 --> 03:28.850 Let's say pimple form, and you are waiting for some minutes or hours. 03:28.850 --> 03:33.950 And then again, when it is just done, you have to come to computer and do the reconstruction. 03:35.060 --> 03:40.670 So instead of that, what if you just initiate and get back and you can file or find all the case files 03:40.670 --> 03:42.530 that you just need all reconstructed. 03:42.530 --> 03:47.740 It removes all the process of file and if you just need the output, it can be done with an alternate 03:47.740 --> 03:47.920 file. 03:47.920 --> 03:49.990 You can run your own alternate file. 03:49.990 --> 03:55.570 Also just the commands which you want and documentation is like it acts as a record of the simulation 03:55.570 --> 03:56.020 procedure. 03:56.020 --> 04:02.890 If you are sending a openfoam case to someone, and if they have no idea on what are the essential steps 04:02.890 --> 04:05.680 to run the case, then they have to contact you. 04:05.680 --> 04:10.090 But instead of that, if you provide the alternate file, they can open the alternate file and either 04:10.090 --> 04:14.950 know what are the commands that are needed, or they can just initiate the alternate file and they can 04:14.950 --> 04:16.480 get all the data that is needed. 04:16.480 --> 04:18.880 And all they have to do is just post-process. 04:19.240 --> 04:22.630 They don't even have to know how the case was set up or how to run it. 04:23.620 --> 04:30.070 So automation with all clean file is like it cleans up files from previous simulation to prepare for 04:30.070 --> 04:30.730 a new run. 04:30.760 --> 04:38.180 So it just sits back the entire case to its original version so you can run from scratch. 04:38.180 --> 04:42.080 And it also ensures a fresh start for simulation by removing old data. 04:42.500 --> 04:45.230 So that is the benefit of using all clean files. 04:46.430 --> 04:52.580 So to create an alternate file we are just going to, uh, remove mesh files and deletion. 04:52.700 --> 04:56.180 Uh, we are going to delete the time directories and the clearing log files. 04:56.180 --> 04:56.540 Sorry. 04:56.540 --> 04:58.680 It has to say automation with all clean files. 04:58.710 --> 05:05.040 This slide is about all clean, and it is also a shell script that removes specified specified files 05:05.040 --> 05:05.850 and directories. 05:07.170 --> 05:10.410 So this is an example of all clean files. 05:10.440 --> 05:11.580 Sorry, it's not all done. 05:11.580 --> 05:12.630 It's all clean. 05:13.800 --> 05:16.290 So it removes the constant polymesh folder. 05:16.290 --> 05:16.530 Again. 05:16.530 --> 05:19.350 It removes all the time steps from 0 to 9. 05:19.350 --> 05:24.570 And it also removes the post-processing folder where we had the force coefficient, and it also removes 05:24.570 --> 05:26.910 any log files when you are running all run file. 05:26.910 --> 05:32.160 Since you will not be getting anything on the terminal, it would be stored as a log file. 05:32.160 --> 05:34.500 So that's what documenting also means. 05:34.500 --> 05:43.050 So to initiate this you can use bash space, dot slash or all clean when you are on a windows machine. 05:43.620 --> 05:47.300 But when you are on an ubuntu machine just dot slash all clean is fine. 05:48.560 --> 05:52.970 So we will be seeing some examples from the tutorials folder now. 05:53.660 --> 06:02.480 Okay, when I was talking about uh tutorials folder I was saying that it can be copied and run even 06:02.480 --> 06:05.420 without knowing what that simulation actually means. 06:05.660 --> 06:08.870 So I will open the tutorial folder here. 06:10.190 --> 06:18.290 So just going to go to the run directory and open the explorer here. 06:19.880 --> 06:22.640 So we have a copy of tutorials here. 06:22.880 --> 06:26.330 So let's take incompressible okay. 06:26.720 --> 06:33.800 In incompressible let's take simple form and let's see airfoil 2D. 06:34.010 --> 06:36.830 And let's see what it has in the old run file. 06:40.910 --> 06:43.940 See it has a different set of commands. 06:43.940 --> 06:46.160 It says restore zero directory. 06:46.160 --> 06:50.330 If you try to run this command in your command prompt it won't run. 06:50.330 --> 06:52.040 But through shell scripts it will. 06:52.370 --> 06:58.460 You see this is the header and setting we are setting parallel to true because we have a if else condition 06:58.460 --> 06:58.970 here. 07:01.480 --> 07:02.020 Okay. 07:02.020 --> 07:03.880 It is restoring the zero directory. 07:03.880 --> 07:07.540 It means it is copying the zero dot original file and putting it in zero. 07:07.540 --> 07:10.660 So that is what zero restore zero directory means. 07:10.780 --> 07:19.300 Then we are doing zero hyphen d constant polymesh and uh slash slash copy rf constant slash polymesh 07:19.300 --> 07:21.730 dot original two constant slash polymesh. 07:21.730 --> 07:23.050 So what this does. 07:23.170 --> 07:27.430 We have polymesh original because we don't want to mess with the original polymesh file. 07:28.180 --> 07:34.870 So this command essentially copies the polymerized or original and pastes it in the new name Polymesh. 07:34.870 --> 07:36.850 So that is what this command means. 07:37.300 --> 07:37.570 Okay. 07:38.380 --> 07:43.000 And we are entering the if else condition we have set the parallel to true. 07:43.000 --> 07:46.900 So when parallel is true then we will be running decompose power. 07:47.650 --> 07:50.670 Then run parallel would be get application. 07:50.670 --> 07:53.910 It would be in a dollar for a reference. 07:53.910 --> 07:58.560 So it would get the application from control dict and it will run that command here. 07:58.560 --> 08:00.240 So it would be running in parallel. 08:00.240 --> 08:07.470 And we have run application reconstruct part to reconstruct whatever is decomposed if it is parallel. 08:07.470 --> 08:12.840 But when the parallel is set to false then it would just get the application and run it. 08:12.840 --> 08:15.060 So it is just basic if else condition. 08:16.050 --> 08:18.810 Now we will see all clean file. 08:20.670 --> 08:23.550 So it just says clean case zero. 08:23.550 --> 08:26.010 It is going to clean all the time steps. 08:26.310 --> 08:30.510 It is same as form less times but in a shell script way. 08:30.510 --> 08:33.600 And we have our rm minus rf constants slash polymesh. 08:33.600 --> 08:38.580 So it is going to delete the polymesh which we just duplicated from polymesh dot origin. 08:40.020 --> 08:46.710 Okay, for tutorial purpose I am going to copy this and put it in this week's folder. 08:47.220 --> 08:48.900 When you get it it would be empty. 08:51.150 --> 08:53.790 Okay, now we have this airfoil. 08:55.560 --> 09:02.550 Okay, now what I'm going to do is I'm not going to do any sort of like block mesh or run anything because 09:02.550 --> 09:03.800 it already has polymers. 09:03.800 --> 09:12.170 So I'm just going to initiate the all run file and you can see that it is running everything one by 09:12.170 --> 09:12.590 one. 09:13.880 --> 09:16.790 First it restored zero dot original to zero. 09:16.820 --> 09:22.070 Yes it happened and then it did decompose part as it happened. 09:22.070 --> 09:25.940 And it is running simple form keys on eight processes. 09:26.090 --> 09:28.790 But you're not getting anything here at all, right? 09:28.790 --> 09:33.980 Because when you are running simple form, it would keep on saying updating the time steps because it 09:33.980 --> 09:37.790 is getting stored in logged or simple form. 09:38.600 --> 09:45.080 So you can open it and always see what was happening with the case. 09:45.470 --> 09:50.120 And you can even post-process this if you are very good at dictionary in Python. 09:50.570 --> 09:53.650 Okay, So this simulation is done. 09:53.650 --> 09:55.510 It is also reconstructing now. 09:55.510 --> 10:01.360 And if you want to monitor reconstruct part, yes you can open it in VSCode or any text editor. 10:01.570 --> 10:08.320 And you can get live updates like all you have to do is maybe change application or refresh the file. 10:09.160 --> 10:14.260 When you change application and come back here, it will just work like change the tab or something. 10:15.100 --> 10:16.630 So mostly that works. 10:17.380 --> 10:17.770 Okay. 10:17.770 --> 10:19.060 So it is reconstructing. 10:19.060 --> 10:20.770 That is all that is important. 10:21.370 --> 10:21.670 Okay. 10:21.670 --> 10:24.250 Now let's just wait for this to end. 10:24.880 --> 10:27.460 It's probably going to end at 500. 10:27.910 --> 10:29.230 Now it is at 300. 10:30.790 --> 10:33.550 Or maybe you can also learn to interrupt. 10:33.730 --> 10:37.510 Just hit Ctrl C and it would be interrupted right there. 10:37.810 --> 10:38.050 Okay. 10:38.050 --> 10:43.500 Because anyways we are going to clean this case we are not interested in running it completely or post-processing 10:43.500 --> 10:43.740 it. 10:43.890 --> 10:47.220 So we will also, uh, run the all clean. 10:47.220 --> 10:49.590 Now you have these many files right. 10:49.590 --> 10:54.240 So you can do bash dot slash all clean. 10:54.390 --> 10:58.230 And you can see that it is deleting all the time steps first. 11:00.630 --> 11:04.530 And then the decomposed processes it deleted all the log file. 11:04.530 --> 11:06.510 It it deleted the zero copy. 11:06.540 --> 11:08.280 It also deleted polymesh. 11:08.280 --> 11:11.970 So now it is just as new as what we copied. 11:12.630 --> 11:15.510 Okay, now you knew all these steps. 11:15.510 --> 11:19.590 In this case, you knew what will happen in the airfoil case. 11:19.590 --> 11:24.600 But let's say something like piece of form in alias. 11:24.600 --> 11:24.900 Okay. 11:24.900 --> 11:30.360 We are not going to see about alias, but you really don't have an idea about alias, right? 11:31.170 --> 11:37.860 But if you want to run this case, okay, then you can open this alternate file and see what are the 11:37.860 --> 11:39.180 commands necessary. 11:39.720 --> 11:44.190 Obviously, when someone gives you this case file, you wouldn't know these are the steps, right? 11:44.550 --> 11:48.870 But we don't really care whether it is there or not. 11:48.870 --> 11:53.670 Like see, we have a command called renumber mesh potential form. 11:54.200 --> 11:59.780 We don't know any of these, but if we still want to get the result out of this, all you have to do 11:59.780 --> 12:00.740 is copy. 12:01.610 --> 12:05.150 Put it wherever you want this to be, run. 12:06.110 --> 12:13.730 Then go to your terminal, enter that folder, then initiate all run file. 12:14.240 --> 12:19.670 That is all that is needed to do this. 12:24.380 --> 12:26.810 See, it is now running Snappy Smash also. 12:28.850 --> 12:31.130 Okay, anyways, I'm just going to interrupt. 12:37.370 --> 12:38.600 I'll interrupt here. 12:39.080 --> 12:39.770 Okay. 12:40.190 --> 12:44.380 Uh, but it is running other commands, so you have to interrupt everything when you are interrupting. 12:45.850 --> 12:47.680 It is just running all the commands. 12:49.000 --> 12:50.170 Okay, I'll clear it. 12:50.770 --> 12:51.100 Okay. 12:51.100 --> 12:52.930 Now we have all of these files. 12:52.960 --> 12:54.280 I'll open all clean. 12:54.280 --> 12:56.020 It is going to be very simple. 12:56.440 --> 12:58.090 You see it cleans K zero. 12:58.090 --> 12:59.800 It deletes the tri surface. 12:59.800 --> 13:02.740 And it also deletes all the decomposed par dict. 13:02.860 --> 13:07.630 Uh, I mean, we have made some changes to decompose par and it is changing it. 13:08.470 --> 13:10.930 We really don't want to understand it as of now. 13:11.200 --> 13:17.020 All we want to know is how to run, all run and all clean files. 13:17.890 --> 13:19.570 Now, see, it is deleting everything. 13:20.050 --> 13:21.610 Now the case is just as new. 13:22.600 --> 13:26.560 So I hope you understood about all run and all clean files. 13:26.560 --> 13:32.920 So if any case you find in tutorial and you want to run it, you can always do it just using ultra clean 13:32.920 --> 13:33.280 files. 13:33.400 --> 13:39.610 And you can also see the commands and try to execute them one by one in terminal and find out what what 13:39.610 --> 13:40.840 each command does. 13:40.990 --> 13:43.000 Or check out the documentation that works too. 13:44.620 --> 13:49.150 Okay, now your, uh, project one would start from here. 13:49.150 --> 13:53.590 So it is flow around a prism with coefficient of drag and clip loss. 13:53.860 --> 13:59.010 So you have to do a flow analysis around a square prism using Openfoam. 13:59.250 --> 14:04.350 So the objective is to analyze the flow characteristics around a square prism and compute the drag coefficient 14:04.350 --> 14:06.180 and lift coefficient using openfoam. 14:06.990 --> 14:12.720 This project will involve mesh generation, setting a boundary condition, running simulation and post-processing 14:12.720 --> 14:15.750 results to obtain and analyze CL plots. 14:16.350 --> 14:19.080 So the duration you can take for this is. 14:19.080 --> 14:25.140 You can take three days for case setup and simulation, two days for plotting and report preparation, 14:25.140 --> 14:27.420 and one day for discussing the report. 14:27.420 --> 14:30.240 If you really want to discuss with me, you can mail to me. 14:31.470 --> 14:33.180 So you can mail us. 14:33.180 --> 14:39.210 And we would get back to you if we have any, uh, comments on that. 14:39.420 --> 14:39.780 Okay. 14:39.780 --> 14:41.730 The project description is like this. 14:42.690 --> 14:48.720 The project involves simulating the flow around a square prism, uh, placed in a uniform flow. 14:48.720 --> 14:50.880 So the students will have to use openfoam. 14:50.880 --> 14:56.400 I mean, you have to use Openfoam to generate the computational mesh using block mesh only, or you 14:56.400 --> 14:57.900 can do it in snappy hex mesh. 14:58.710 --> 15:02.190 You can't import mesh from Ansys or anything like that. 15:02.190 --> 15:09.770 You have to use only Openfoam and you have to set up the boundary condition using the appropriate problem. 15:09.770 --> 15:15.710 Like if you are using transient or turbulent, then you can have higher Reynolds number. 15:15.710 --> 15:20.060 But if you are trying to make a steady state laminar case, then you have to keep it very low. 15:20.060 --> 15:25.340 So set up the boundary conditions appropriately and run the simulation using a suitable solver for that 15:25.340 --> 15:25.940 problem. 15:26.750 --> 15:28.970 So you can decide whatever you want to do. 15:29.210 --> 15:35.600 Then you have to extract and analyze the force coefficient CL either using Excel or foam monitor. 15:35.630 --> 15:37.490 Then you can take screenshots from there. 15:37.520 --> 15:42.410 Then you can plot the KD and CL values over time or against other relevant parameters. 15:42.410 --> 15:44.000 If you are doing with Excel. 15:44.480 --> 15:45.050 Then you can. 15:45.080 --> 15:49.460 You have to interpret the results and discuss the flow characteristics observed around the prism. 15:49.550 --> 15:54.230 So this comes with the knowledge of CFD and it is not constrained to knowledge of Openfoam. 15:55.220 --> 16:01.690 So you have to interpret and discuss what that result or value from the simulation actually means. 16:02.230 --> 16:05.560 So the description would be as like this. 16:05.560 --> 16:07.330 Prepare a geometry 2D or 3D. 16:07.330 --> 16:08.890 It's up to you of a square prism. 16:09.730 --> 16:12.460 Then mesh it using block mesh or snap x mesh. 16:12.460 --> 16:16.120 Then ensure the mesh is refined around the prism to capture the boundary layer. 16:16.120 --> 16:17.350 If it is, snap a hex mesh. 16:17.350 --> 16:20.890 You can also use uh, add layers. 16:20.890 --> 16:24.850 Then you have to specify the proper boundary condition setup. 16:25.060 --> 16:33.610 Then choose the solver properly and it is highly recommended to use K-omega SST turbulence model and 16:33.610 --> 16:35.260 set the maximum SEO as one. 16:35.650 --> 16:40.660 Include the necessary function objects to calculate force coefficient postprocess using Paraview. 16:40.750 --> 16:42.310 Study the streamlines. 16:42.310 --> 16:45.070 Plot the CL graph uh. 16:45.070 --> 16:48.420 You can use either for Monitor monitor or Excel. 16:48.750 --> 16:51.930 Then you have to make a detailed report. 16:51.930 --> 16:56.700 Either you you can keep it, uh, for your own reference, or you can mail us. 16:56.700 --> 16:58.890 And we will get back to you with the comments. 16:59.880 --> 17:03.180 So you can work on this question. 17:03.180 --> 17:07.500 You can take the PDF for the question or details, and you can do this. 17:07.740 --> 17:10.770 If you have any questions, please feel free to contact me. 17:10.800 --> 17:12.000 See you in the next class. 17:12.000 --> 17:12.630 Thank you.