WEBVTT 00:00.170 --> 00:00.980 Hello everyone. 00:00.980 --> 00:04.700 Welcome back to the CFD using Openfoam beginner to intermediate course. 00:05.300 --> 00:06.650 This is our class seven. 00:06.650 --> 00:10.370 In this class we are going to see refinement box feature in snappy x mesh. 00:11.570 --> 00:15.920 Our tutorial is on external aerodynamics which is the classic motorbike case. 00:16.700 --> 00:23.390 We are also going to plot force coefficients which are drag coefficient, lift coefficient, CD seal 00:23.390 --> 00:25.550 and so on using new plot. 00:25.550 --> 00:29.460 And we will also be exporting the Post-processed data to Excel. 00:29.490 --> 00:30.450 To plot this. 00:32.040 --> 00:37.710 So we are going to see how to include a refinement region inside the entire snap x mesh. 00:37.830 --> 00:42.480 So as you can see, this is uh, snap mesh file screenshot. 00:42.570 --> 00:44.730 We are defining the motorbike dot obj. 00:44.880 --> 00:46.590 And that is the geometry here. 00:46.590 --> 00:49.350 And we are assigning it to the group motorbike. 00:49.350 --> 00:55.100 And we are defining something called refinement box under the geometry function, which means apart 00:55.100 --> 01:00.230 from motorbike dot obj, we are also having a new set of refinement box. 01:01.130 --> 01:07.220 So this refinement box is treated as a new geometry under which there will be refinement. 01:07.370 --> 01:07.700 Okay. 01:07.700 --> 01:15.620 So the refinement box is defined in such a way that you just need two points to define an entire box. 01:15.620 --> 01:21.390 So you just need the minimum point and the maximum point to define a box. 01:21.390 --> 01:25.740 So the minimum point would be minus one -0.70. 01:25.740 --> 01:31.560 So if you take a cuboid uh and draw the major diagonal it will have two points. 01:31.560 --> 01:32.550 One would be minimum. 01:32.550 --> 01:33.480 One would be maximum. 01:33.480 --> 01:35.880 So that is what this refinement box defines. 01:36.660 --> 01:45.400 We just want to imagine it better try to plot it in a 3D and you would know, uh, using Python or any 01:45.400 --> 01:47.260 programming software you are comfortable with. 01:47.590 --> 01:50.170 Sorry, programming language you are comfortable with. 01:50.440 --> 01:54.220 Then you have the Geometry of Refinement box now. 01:54.220 --> 01:59.590 So what you are going to do is you are going to use a function called refinement region, under which 01:59.590 --> 02:05.080 you are assigning the refinement box as the location where you want a refinement, and you are going 02:05.090 --> 02:08.360 to say move inside, which means you are trying to refine it. 02:08.360 --> 02:13.970 Inside this box you can also do the negative, but mostly it is used only for refinement inside the 02:13.970 --> 02:14.180 box. 02:14.180 --> 02:16.520 So we will stick with more inside. 02:17.270 --> 02:24.200 And we can also set the levels which is 115 for uh for refinements. 02:24.200 --> 02:30.910 So the 115 is a standard value which you might have to use and four is the number of refinement levels. 02:30.910 --> 02:34.960 So we will also see the file and see how this is getting implemented. 02:35.350 --> 02:37.930 So I will go to the case file. 02:37.930 --> 02:45.400 We have zero constant system and paraview under system we have snappy hex mesh dict as usual. 02:47.320 --> 02:49.450 So I am going inside this. 02:49.450 --> 02:57.140 And you can see that we have refinement box And this refinement box is referenced when you go below 02:57.140 --> 02:59.450 and you have refinement surfaces. 02:59.450 --> 03:01.430 This is one such area. 03:01.430 --> 03:03.890 And similarly we also have refinement regions. 03:03.890 --> 03:06.560 So this is the one which you saw in the PPT. 03:06.860 --> 03:12.350 Generally if you don't want the refinement region all you can do is just select this, put it in a comment 03:12.350 --> 03:13.640 and this would be fine. 03:13.640 --> 03:18.990 So this should work even without a refinement box. 03:18.990 --> 03:24.810 But you can't remove this function entirely, so you just have to remove the values and, uh, make 03:24.810 --> 03:25.800 the function stay. 03:25.800 --> 03:27.630 In this case, we want a refinement box. 03:27.630 --> 03:29.010 So I will have it. 03:29.970 --> 03:33.090 So we are just going to generate the snappy mesh now. 03:33.090 --> 03:37.650 So if you remember the process the first process is to generate the block mesh. 03:41.080 --> 03:42.580 It is throwing an error. 03:43.570 --> 03:49.180 Okay, I am not inside the motorbike region so I have to enter the folder. 03:50.290 --> 03:53.020 So this is the mistake you should not make. 03:53.020 --> 03:56.410 Always type less and make sure that you have the zero constant and system. 03:57.100 --> 04:00.460 Okay, now I am going to run the blog mesh. 04:01.870 --> 04:08.220 Okay, now the second thing is our face feature extract. 04:11.010 --> 04:13.200 Now that is also done. 04:14.130 --> 04:14.250 Okay. 04:14.250 --> 04:17.820 Now we just have to run this snappy hex mesh dict. 04:17.820 --> 04:21.540 But before that we are going to see the compose product file. 04:23.010 --> 04:24.390 Now I have eight cores. 04:24.390 --> 04:26.640 So I put eight and the method is scotch. 04:26.640 --> 04:30.130 So what I'm going to do is I'm going to decompose power. 04:36.010 --> 04:42.580 And I'm going to run snappy Higgs mesh in parallel. 04:51.370 --> 04:53.990 So I'll get back to you once this is over. 04:55.250 --> 05:01.550 Now the snappy hex mesh is done so I can reconstruct it now. 05:01.880 --> 05:08.210 So I'll do reconstruct per mesh if and constant. 05:16.340 --> 05:16.850 Okay. 05:16.850 --> 05:23.010 Now I can safely remove all the processor files because it's not needed anymore. 05:23.910 --> 05:28.770 Okay, I will open the paraview file and show you the mesh which we just generated. 05:29.970 --> 05:30.300 Okay. 05:30.300 --> 05:36.120 Because I did not give a initiative on what the geometry actually is. 05:38.730 --> 05:41.250 As you can see, we have a big mesh. 05:41.510 --> 05:45.350 This is our fluid domain and we have a bike inside a nice bike. 05:45.380 --> 05:48.530 Okay, so we are just going to see the bike now. 05:49.280 --> 05:50.960 I'll click on motor bike group. 05:50.960 --> 05:54.170 Turn off incompressible sorry internal mesh. 05:55.520 --> 05:57.950 And I'll choose surface with edges. 05:58.040 --> 06:01.850 So this meshing took a lot of time. 06:02.330 --> 06:02.780 Okay. 06:02.780 --> 06:07.410 You can see it took like 28.24 seconds. 06:07.440 --> 06:07.920 Okay. 06:08.940 --> 06:11.430 So it took really a lot of time. 06:11.430 --> 06:14.670 So when that's why we have a bad mesh. 06:14.970 --> 06:18.120 Uh, but still we have a bad mesh. 06:18.120 --> 06:23.010 So if you are going to refine it further, it's going to take still more time. 06:23.010 --> 06:26.190 So for demonstration purpose, I just kept it low. 06:26.220 --> 06:26.670 Okay. 06:26.940 --> 06:32.680 So this is the bike and we are going to do the external aerodynamic analysis on this. 06:32.680 --> 06:35.170 This is not the best mesh someone could use. 06:35.170 --> 06:41.830 But for demonstration this would be just fine because we are just learning and we want to learn faster. 06:42.850 --> 06:43.390 Okay. 06:44.530 --> 06:51.130 Now we will see what is uh, external aerodynamics in terms of openfoam. 06:51.130 --> 06:55.440 So first we run the block mesh and we ran surface feature extract. 06:55.440 --> 06:57.090 Then we did decompose power. 06:57.090 --> 07:00.720 And also we did the snappy x mesh parallel over right now. 07:00.720 --> 07:03.360 And then we reconstructed power also. 07:03.360 --> 07:06.420 So we have reconstructed everything related to mesh. 07:06.600 --> 07:09.960 But now we have to start decomposing and running the case. 07:09.960 --> 07:10.500 Right. 07:10.890 --> 07:20.140 But you can see when I try to decompose it won't be getting all the files properly because we have something 07:20.140 --> 07:21.370 called zero dot original. 07:22.150 --> 07:27.400 When you copy a case from tutorials, it is going to come like this. 07:27.430 --> 07:29.950 In most cases it's going to be like zero dot original. 07:29.950 --> 07:36.010 When it is like this, Openfoam can't realize that this is the zero file, and it won't put it inside 07:36.010 --> 07:39.490 the constant folder of each processor. 07:40.510 --> 07:46.040 So Openfoam can't realize that this is the actual zero file and decompose it properly. 07:46.040 --> 07:49.730 So we have to copy this original and put it in a normal zero file. 07:49.730 --> 07:55.490 This is there because if you are wanting to make any changes to the boundary conditions boundary files, 07:55.880 --> 07:59.180 uh, you should not mess up with the original file. 07:59.180 --> 08:00.650 So that's why we have this. 08:01.100 --> 08:09.840 So what we can do is either you just copy paste it here and rename it to zero works fine, no problem. 08:09.840 --> 08:18.510 But if you want to do it the cool way, you can do CP hyphen, r zero dot original and zero. 08:18.960 --> 08:21.750 That would still do the same thing but through the terminal. 08:22.410 --> 08:25.620 Okay, now we will see the boundary files. 08:26.220 --> 08:32.690 So you can see that there is something called include file include folder which we have not encountered 08:32.690 --> 08:33.200 till now. 08:33.200 --> 08:35.990 So I'll explain it what it what it means. 08:36.530 --> 08:43.790 So if I go to include we have three files initial conditions print backup or patches and then fix it 08:43.790 --> 08:44.090 inlet. 08:44.090 --> 08:45.710 Just remember these names. 08:46.640 --> 08:48.890 Now I will go inside the you file. 08:50.270 --> 08:57.420 Since Openfoam works with C plus plus we can call in another file and use the functions inside it. 08:57.540 --> 09:01.590 So we are including the file called initial conditions. 09:01.920 --> 09:07.950 And uh, from initial conditions we are taking in the value of inlet. 09:08.070 --> 09:08.400 Okay. 09:08.400 --> 09:11.580 So we have initial conditions file here. 09:11.850 --> 09:14.130 I'll just open it so you understand it better. 09:16.230 --> 09:16.410 Okay. 09:16.410 --> 09:20.960 The initial conditions is saying the flow velocity is this pressure, is this turbulence. 09:20.960 --> 09:24.110 Kinetic energy is this and turbulent omega is this. 09:24.140 --> 09:30.980 Now when I go to you file you can see we don't have any inlet patch because for that we have fixed inlet 09:30.980 --> 09:31.670 patch here. 09:33.080 --> 09:35.060 See we have the inlet patch here. 09:35.060 --> 09:40.670 We are just referencing it here, this location so it can get the function from there. 09:40.760 --> 09:46.160 And we also include the set constraint types function which is from include etc.. 09:46.160 --> 09:53.240 So this is mandatory to include this so that Openfoam can understand that these references are getting 09:53.240 --> 09:54.680 uh referenced properly. 09:55.520 --> 09:58.910 Then we are referencing front and back upper batches also. 09:58.910 --> 10:00.560 So it need not be like this. 10:00.560 --> 10:06.670 You can just copy and paste this here, but the purpose of having this is when you are just mentioning 10:06.670 --> 10:07.870 include initial condition. 10:07.870 --> 10:14.260 Instead of mentioning all of the values in different files, you just put it here and whatever is necessary 10:14.260 --> 10:15.460 it would be referenced. 10:15.520 --> 10:17.530 So I will open. 10:18.100 --> 10:24.970 Let's say I will open k file because we have k file that we are referencing initial condition. 10:24.970 --> 10:31.130 We are including the fixed inlet so we don't have to type it one by one in all the files. 10:31.160 --> 10:38.000 Now, if you are, uh, wanting to change just the fixed inlet value instead of changing the value in 10:38.000 --> 10:43.670 every file, all you have to do is change it in the one file and it will get referenced to all the files. 10:43.670 --> 10:46.790 So that is the, uh, only motive of doing this. 10:46.790 --> 10:49.370 I will open a different backupper patches now. 10:51.860 --> 10:55.020 It says upper wall slip front and back is also slip. 10:55.020 --> 11:01.440 So when we are seeing any file, all you have to do is reference the upper back, uh, friend patch. 11:01.440 --> 11:03.450 And it would take it as lip. 11:03.540 --> 11:06.300 So it happens with all the files you see. 11:06.300 --> 11:11.040 So that is the, uh, use of having this kind of include folder. 11:11.040 --> 11:13.650 Otherwise these files are just normal thing. 11:13.800 --> 11:16.350 And you can play with the values if you want. 11:16.350 --> 11:24.490 In this case we have, uh, set the initial condition as 20m/s in X direction. 11:25.180 --> 11:25.780 Okay. 11:25.780 --> 11:28.210 Now we will see what is there in the constant folder. 11:28.210 --> 11:32.410 We have the tri surface where we have put the motor vector obj instead of SDL. 11:32.410 --> 11:34.420 We used obj file. 11:34.690 --> 11:35.860 We already saw this. 11:35.860 --> 11:46.320 So uh we have the transport properties We are using a Newtonian model with kinematic viscosity of 1.5 11:46.320 --> 11:47.790 into ten power minus five. 11:48.780 --> 11:55.200 And we have turbulence properties where we are using k omega SST because it works well with waltz. 11:55.440 --> 11:58.020 We are trying to do an external aerodynamics. 11:58.020 --> 12:01.230 So k omega SST is one of the best. 12:01.470 --> 12:06.910 So we already saw how to do k in the previous class, but we did not see K Omega. 12:06.910 --> 12:10.000 So that's why we are seeing this kind of thing. 12:10.000 --> 12:12.310 So you also understand K omega better. 12:13.930 --> 12:20.860 So to do k omega the essential files are k omega obviously and new t okay. 12:20.860 --> 12:25.150 Now we go to the system as usual we have block mesh decompose predict. 12:25.240 --> 12:31.070 And we have a scheme for solution mesh quality snappy and uh surface feature extract. 12:31.070 --> 12:31.760 Everything is fine. 12:31.760 --> 12:34.430 But we also have a new file called force coefficients. 12:35.090 --> 12:42.170 If I go inside force coefficient, you will see that there is a function which says that I pass force 12:42.170 --> 12:42.920 coefficient. 12:42.920 --> 12:45.590 It is referencing a library called forces. 12:45.590 --> 12:46.070 Right. 12:46.070 --> 12:49.160 Control is saying time step and the time interval is one. 12:49.160 --> 12:51.170 This is all intuitively understandable. 12:51.320 --> 12:56.260 And the log is saying yes, uh, to plot it in logarithmic scale. 12:57.070 --> 13:03.670 If you have not got what this file means is it is just going to, uh, take the values from here. 13:03.670 --> 13:05.770 So that's why we are plotting it in log. 13:06.490 --> 13:10.780 And we are trying to get the data from the patch motorbike group. 13:10.780 --> 13:15.670 If you see the mesh, I have plotted only the motorbike group here. 13:15.670 --> 13:22.790 So on all these mesh points the calculation will be done for CDC, LCR and so on. 13:23.120 --> 13:27.200 So we have to define the reference values like density. 13:27.200 --> 13:29.840 In this case the density is taken as one. 13:29.840 --> 13:36.260 For simplification you can work with original uh exact values of density if you want. 13:36.890 --> 13:39.710 Then we want to define the lift direction. 13:39.710 --> 13:43.920 So if you see this geometry the lift direction would be positive z axis. 13:43.920 --> 13:45.180 That's what we have mentioned. 13:45.180 --> 13:47.880 And the drag direction would be positive x. 13:48.720 --> 13:51.390 So that's what we have mentioned again. 13:52.290 --> 13:59.850 And the coefficient of uh sorry c of r which is like the center of rotation not the coefficient. 13:59.850 --> 14:00.450 I'm so sorry. 14:00.450 --> 14:01.980 It is center of rotation. 14:02.130 --> 14:05.250 That would be 0.72 comma zero comma zero. 14:05.250 --> 14:06.610 Where did this value come from? 14:07.390 --> 14:09.040 I will turn on that axis grid. 14:09.070 --> 14:14.230 You can see that this point is kind of the center of this entire geometry. 14:14.230 --> 14:17.410 So 0.72 makes sense right. 14:18.040 --> 14:20.740 So that is why we took 0.72. 14:20.980 --> 14:22.990 And we want the pitch axis. 14:22.990 --> 14:27.910 So uh in which axis it is going to pitch for drag and lift. 14:28.120 --> 14:35.460 So that is why, Because, uh, the if you take the normal or perpendicular, it's going to be y. 14:35.490 --> 14:38.190 So this will, uh, pitch along the y direction. 14:38.190 --> 14:44.220 So we are mentioning y and magnitude of u infinite, which is the free stream velocity in this case 14:44.220 --> 14:44.940 is 20. 14:45.780 --> 14:51.420 And we also have to do the length reference and the area reference values so that the CDC values are 14:51.420 --> 14:57.820 getting calculated properly because we need reference values Openfoam can't take these values from the 14:57.820 --> 14:59.740 geometry, so we have to define it. 14:59.830 --> 15:06.940 But just calling this, uh, putting this folder in system directory is not going to make it work. 15:06.940 --> 15:07.270 Right. 15:07.270 --> 15:10.480 If you understood openfoam by now, it's not going to make it work. 15:10.480 --> 15:12.700 We have to reference it somewhere. 15:12.850 --> 15:17.500 So the way to reference it is in control. 15:17.830 --> 15:19.010 You open control dict. 15:19.010 --> 15:23.540 At the end, you just open a new function called functions, and inside that you just put this function, 15:23.540 --> 15:29.480 call the force coefficient and it will reference to the function of functions in force coefficient one 15:29.480 --> 15:30.170 function. 15:31.370 --> 15:34.970 So we are having this include force coefficient. 15:34.970 --> 15:36.830 So it is going to take a reference from there. 15:36.830 --> 15:38.210 And it will plot all of these. 15:38.210 --> 15:43.200 But if you don't want to do this then you can just copy the entire thing. 15:43.200 --> 15:46.890 Then just replace it under functions in Openfoam. 15:46.890 --> 15:48.240 It will, sorry, controlled it. 15:48.240 --> 15:54.780 It will just still work fine, but it's not going to be a nice way to keep your control dict. 15:54.780 --> 15:58.380 It's going to be messy when you are going to work with a lot of functions later. 15:59.010 --> 16:04.170 So it's always fine and better to have things in different files and referencing it. 16:04.170 --> 16:05.700 That's how C plus plus works. 16:05.880 --> 16:09.740 So we got how to set up the force coefficients also. 16:09.740 --> 16:15.590 So I would advise you to download some geometry from Grabcad like a car model. 16:15.590 --> 16:17.720 You know how to set up snappy hex mesh now. 16:17.720 --> 16:20.330 So set up a car case. 16:20.930 --> 16:24.470 Try to do this case in car instead of just this bike. 16:24.830 --> 16:25.340 Okay. 16:25.340 --> 16:31.410 So I have given this bike, uh, geometry already, but it doesn't come with the tutorials directly. 16:31.410 --> 16:37.290 We have to find it inside the under tutorials we have resources folder. 16:37.290 --> 16:39.390 Under resources we have geometries. 16:39.390 --> 16:40.290 Under geometry. 16:40.290 --> 16:46.680 You will have this uh motorbike geometry which you have to download a copy and paste it in the constant 16:46.680 --> 16:53.190 folder so you will understand it better when you see uh, and understand all run files. 16:53.190 --> 16:54.790 So for now you just don't worry. 16:54.790 --> 17:00.760 You can download and do a machine using snappy hex mesh for any geometry and work with it. 17:01.510 --> 17:04.270 Okay, now we will see what we have to do next. 17:04.390 --> 17:08.710 Now we have set up everything so we can decompose power and run this case. 17:08.740 --> 17:09.220 Right? 17:10.180 --> 17:10.750 Yes. 17:11.440 --> 17:13.390 So I will do decompose power. 17:14.770 --> 17:16.780 It's going to decompose the case. 17:17.410 --> 17:19.010 I hope it doesn't throw an error. 17:21.290 --> 17:22.940 Yeah, it didn't throw any error. 17:24.320 --> 17:24.620 Okay. 17:25.010 --> 17:27.380 All I have to do is initiate this case. 17:27.380 --> 17:31.700 So this case is, uh, I'll go to control dict. 17:32.240 --> 17:33.560 It's a simple form case. 17:33.560 --> 17:34.640 It's a steady state case. 17:34.640 --> 17:41.000 So I'm just going to do mpirun NP eight. 17:41.720 --> 17:42.860 Simple form. 17:43.600 --> 17:47.080 Parallel and it enter. 17:48.760 --> 17:51.040 So it is going to take a bit of time. 17:51.040 --> 17:55.720 I'll get back to you after it is over, but you can notice something different here. 17:55.930 --> 17:59.320 It is also giving you the values of CD and the. 18:02.560 --> 18:04.750 Vectors of CD. 18:05.440 --> 18:08.540 And we have CL and vectors of CL also. 18:08.540 --> 18:10.280 So we also have like. 18:10.490 --> 18:14.360 Coefficient of moment for pitch, roll and yaw and all. 18:15.080 --> 18:16.790 Mostly we just use CNNs here. 18:16.790 --> 18:23.540 So I'll get back to you once the simulation is over the simulation is over, but still the solution 18:23.540 --> 18:24.770 is not converged. 18:25.160 --> 18:26.360 As you can see. 18:26.510 --> 18:30.800 Uh, but I stopped it at the time of 500 because it's taking so much time. 18:30.810 --> 18:32.520 It's already four seconds. 18:32.880 --> 18:35.940 But if you want to run it completely, you can run it. 18:36.240 --> 18:39.360 But, uh, for demonstration purpose, this would just be fine. 18:39.360 --> 18:39.600 Okay? 18:39.600 --> 18:42.390 We can take the latest time step and work with it. 18:43.620 --> 18:49.890 So, uh, I have run the decomposed case, as you can see. 18:49.890 --> 18:51.960 Now, I have to reconstruct it. 18:53.130 --> 18:58.240 So if you remember the command to reconstruct it faster. 19:01.690 --> 19:03.220 Yeah, I have it. 19:27.210 --> 19:29.820 Okay, now the reconstruction is done. 19:29.820 --> 19:34.980 I can safely delete all the processor files, though. 19:34.980 --> 19:36.750 It is going to take a lot of time. 19:37.020 --> 19:41.370 Can just go here and click on refresh. 19:41.580 --> 19:44.470 So it is going to load all the files. 19:44.470 --> 19:46.030 This is needed for us. 19:46.600 --> 19:48.370 So I'll go to Internal mesh. 19:48.370 --> 19:49.360 Click on apply. 19:51.520 --> 19:52.870 And I will take a. 19:55.360 --> 19:56.890 Sliced plane. 19:57.970 --> 20:00.280 So I want it y normal. 20:04.870 --> 20:05.290 Okay. 20:06.550 --> 20:07.730 Don't worry about this. 20:08.720 --> 20:10.370 We'll go to normal. 20:11.030 --> 20:12.470 This is the pressure fields. 20:12.500 --> 20:15.530 We'll go to Velocity Field at the last time step. 20:16.880 --> 20:21.020 So as you can see, we have the motorbike case. 20:21.020 --> 20:23.570 And you can see the velocity profile here. 20:23.600 --> 20:26.480 If you want to plot the streamlines of course you can. 20:27.140 --> 20:29.870 But this tutorial is not about this, right? 20:29.900 --> 20:31.870 This is about plotting force coefficients. 20:31.870 --> 20:34.270 So let's look at how to do that. 20:35.260 --> 20:37.630 Okay so we have done all of these. 20:38.950 --> 20:44.740 Now we also saw how to set up the function and what everything in the function means. 20:44.920 --> 20:52.180 Since we now know how to set up the case and set up the function to get the force coefficients, you 20:52.180 --> 20:54.370 can now see how to post process this data. 20:54.670 --> 21:01.400 So to do that you can go to your working directory and you will see a folder called post-processing 21:01.400 --> 21:02.390 just got created. 21:02.480 --> 21:07.100 If you go here you will see the function name which is force coefficients one in our case. 21:07.520 --> 21:09.830 Under that you will have the zero folder. 21:09.830 --> 21:19.190 Under that you have the force or coefficient dot that if you open it, it is just long list of files 21:19.200 --> 21:30.090 with just generated and stored the values of Cdecl and their vectors or components of cdecl and coefficient 21:30.090 --> 21:31.320 of moment, and so on. 21:32.280 --> 21:39.090 So you can basically import this into Python also and post-process it for uh, plotting. 21:39.750 --> 21:44.710 But Openfoam gives you a easy way which is called foam monitor. 21:44.710 --> 21:46.570 So we are going to do that now. 21:46.840 --> 21:53.380 So what we are going to do is we are going to create a plot of the coefficient things. 21:53.380 --> 21:58.240 So the command is foam monitor space hyphen. 21:58.360 --> 22:00.760 This hyphen s l is for log. 22:00.760 --> 22:04.360 So if you don't want a log plot you don't have to include that hyphen L. 22:04.360 --> 22:05.560 We will also do that. 22:05.560 --> 22:11.160 So the location of that file is post processing force coefficients one. 22:11.160 --> 22:12.420 Under that we have zero. 22:12.420 --> 22:14.010 Under that we have coefficient on that. 22:14.430 --> 22:22.290 So what it means is we are calling the application form monitor which is based on Gnuplot. 22:22.290 --> 22:22.890 Actually. 22:23.010 --> 22:28.410 Then we want to log plot, then the location or the path to the coefficient of that file. 22:28.950 --> 22:32.740 Then you just hit enter and you will be able to see the graph. 22:33.010 --> 22:36.880 So you can see we have the legends here. 22:36.880 --> 22:40.210 So the CD is less than one. 22:40.540 --> 22:42.880 And you see we have CL. 22:42.880 --> 22:45.430 So that is also less than one. 22:45.550 --> 22:46.390 We have all this. 22:46.390 --> 22:49.480 So this is a log plot as you can see from the y axis. 22:50.140 --> 22:54.040 But if you don't want the log plot let's just assume that you don't want a log plot. 22:54.220 --> 22:59.120 And when you close the application of new block, just hit Ctrl C. 22:59.120 --> 23:01.610 Otherwise it's going to respawn and come again. 23:02.570 --> 23:04.820 Okay now I will remove that hyphen L. 23:07.250 --> 23:12.620 You can see we just got a normal plot where everything is less than one and close to zero. 23:12.920 --> 23:15.980 So we are not going to see much from this graph. 23:16.760 --> 23:23.580 If you want to zoom and all you can actually do zoom and things like that. 23:28.410 --> 23:30.210 Yeah, it all happens here. 23:30.210 --> 23:32.010 So it just works. 23:32.010 --> 23:33.630 Same as Gnuplot. 23:33.660 --> 23:38.040 I'll close this and hit Ctrl C, otherwise it's going to respawn again and again. 23:39.150 --> 23:46.490 Okay, now we are going to export this post-process data to Excel, and we will try to plot the force 23:46.490 --> 23:48.470 coefficients values using Excel. 23:48.980 --> 23:51.560 Okay, now I will open Excel. 23:53.510 --> 23:56.300 I'll open a blank sheet. 23:57.740 --> 23:58.100 Okay. 23:58.100 --> 24:01.910 If you are just working with LibreOffice it is still fine. 24:02.750 --> 24:02.870 Okay. 24:02.870 --> 24:05.510 What I'm going to do is I'm going to copy this entire thing. 24:05.510 --> 24:17.040 Instead of doing that, I'll go here and probably hold shift and click on this and then. 24:20.370 --> 24:23.910 Just copy till here. 24:24.840 --> 24:29.070 So this would copy everything control C and control V. 24:29.070 --> 24:30.750 You can also import if you want. 24:30.750 --> 24:33.760 I just find it easier when I do this. 24:33.760 --> 24:43.000 So since this is a steady state case, first few iteration would be totally, uh, senseless like these 24:43.000 --> 24:43.360 things. 24:43.360 --> 24:48.280 Also, we don't want the components of cdecl, so I will remove all of these. 24:48.280 --> 24:50.650 We don't want the coefficient of moment at all. 24:51.520 --> 24:54.190 So I will delete all of these. 24:54.190 --> 24:56.780 We just need coefficient of drag and lift against time. 24:56.780 --> 24:59.690 We just want to see how it got converged against time. 25:00.170 --> 25:05.750 So I will also delete first 9 or 10 data. 25:07.310 --> 25:16.640 Okay now if you just know how to plot in Excel is the same go here and select data. 25:18.080 --> 25:21.340 Okay now we have got the CDC plots. 25:21.340 --> 25:25.180 So you can work on beautifying this graph. 25:26.590 --> 25:29.350 Uh using Excel you can add chart title and so on. 25:29.350 --> 25:33.730 So I just told you how to plot it using Excel, how to import it and all. 25:36.280 --> 25:36.610 Okay. 25:36.610 --> 25:41.920 If you have any questions regarding the content in this video, you can feel free to contact me. 25:42.160 --> 25:43.420 See you in the next class. 25:43.420 --> 25:44.140 Thank you.