Learning Forum

[rrathishubham]

Hello everyone I'm new to ANSYS so please dont mind if this is a really silly one. I'm trying to generate a model of cooling tower using axisymmetric but the problem is that i dont know how to place it at a position to get a proper radius and revolve it around y axis.
I have attached a screenshot of cooling tower in 3d but i want the same in 2d. Please help.

[peteroznewman]

It's good to do an axisymmetric model when you can.

For structural problems, the axis-of-rotation is the Global Y axis. Keep the geometry on the +X side of the Y axis.

For fluids problems, the axis-of-rotation is the Global X axis. Keep the geometry on the +Y side of the X axis.

ANSYS provides two Geometry editors, the newer one is SpaceClaim. There are several tutorials on SpaceClaim in the Tutorials section of this site.  You should become a little skilled at SpaceClaim and learn how to sketch and make a surface.

Please describe what you want to simulate in some detail.

Regards,
Peter

[rrathishubham]

I want to simulate in structure. I have tried a lot of times to create a 2d model but I always get an error saying " No valid bodeis found for 2D analysis".

[peteroznewman]

You didn't say if you are using SpaceClaim or DesignModeler.

After you sketch a closed loop on the XY plane, you need to either:

1. In SpaceClaim: Click the Pull tool or click the 3D mode button or

2. In DesignModeler: Concept > Surfaces from Sketchs > Generate

In either case, you will end up with a surface. This is what you need before you try to transfer geometry into Mechanical.

Regards,
Peter

[rrathishubham]

Thankyou sir for your reply. But how do I specify the distance from y axis?

[peteroznewman]

It depends on whether you are using SpaceClaim or DesignModeler.

[rrathishubham]

I will be using design modeler

[peteroznewman]

In DesignModeler, you click on the Dimension tab, select Horizontal dimension and click on the line and the dotted line of the Y axis.

[rrathishubham]

Thankyou sir.
Also sir, I want to create columns at the base of cooling tower at equal intervals. So how do I do that? I want columns at 20 degrees interval.

[rrathishubham]

Sir, I have prepared the model in Revit and exported it to autocad in dwg format further i exported it to ANSYS in .iges file. And when I try to open mechanical, it says no valid bodies found.

[peteroznewman]

When you add columns at 20 degree intervals, that's not axisymmetric geometry, now it is a 3D model.

A 3D model can be built from a surface of revolution, plus surfaces to represent the columns.

I expect the iges file only had curves and no surfaces. Create surfaces and try to open that in Mechanical.

[rrathishubham]

Sir, it would be very difficult for me to make the model in ANSYS because that thickness of cooling tower varies at every 2.5m and it has a height of 175m. Also it has varying radius at every 2.5m interval.

[peteroznewman]

Do you have a drawing that calls out the thickness and radius as a function of height?

Please also reply with the load you wanted to apply to the cooling tower, was it only gravity?

I recommend you finish the 2D axisymmetric model before you add in the columns.

Then you can start a New Discussion for the 3D model.

[rrathishubham]

Yes, i have the drawing that calls out thickness and radius as function of height.
Loads to be applied on cooling tower: gravity, wind, seismic

[peteroznewman]

Only gravity is an axisymmetric load.  Wind and seismic are not.

I recommend you finish the 2D axisymmetric model with just gravity to build some skill with ANSYS.

Please share the details of the thickness and radius as a function of height.  You can insert an image into your reply of either sections of the drawing or a table.  You can also attach files after you post your reply. Put whatever file you have into a zip file and attach the zip file.

[rrathishubham]

Sir, I'm not able to attach the files, can i get your mail id or something where i can send you the files??

[peteroznewman]

Do you have a zip file?

What is the file size?

When you click on the Attach button, Browse to the zip file and click Upload.

You will see the file upload. Please try again and describe in detail what happens if it does not attach.

[rrathishubham]

Its a zip file and the file size is 5.36 MB. When I select files and try to upload them, it shows 100% uploaded and it redirects me to same page and the files are not uploaded over there.

[peteroznewman]

Create three columns of numbers in a spreadsheet. Copy the three columns out of the spreadsheet and paste into Notepad. Format a line as Preformatted on the pull down in the toolbar. Copy all the lines out of Notepad and paste into that Preformatted line as shown below, except you will have 71 rows. 

height(m)	radius(m) 	thickness(m)

0	20	1

2.5	19.5	1

5	19	1

7.5	18.5	0.95

10	18	0.95

 Alternatively, if you File, Save As the spreadsheet as a Text file and if the file has a .txt file extension, that is another allowed file extension for attaching files to replies. I know you were able to attach a .jpg file at the beginning. You can try to attach a .txt file now.

[rrathishubham]

Sir, details of geometry are attached in text format. 

[peteroznewman]

After you Reply, look at the buttons on the page and an Attach button appears. You have used that above. That is correct.  The problem with the file you attached is that it is empty.

If you copy text out of Notepad, you can paste it directly into the Reply window where you are typing. That is what I did. Try that.

[rrathishubham]

Note: Cooling tower starts from a height of 9.17m from ground as columns has a height of 9.17m 

height from ground (m)	radius (m)	thickness (m)

9.17	58.71998481	1.05

10	58.45077875	1.044153913

12.5	57.64576787	1.032

15	56.84976984	1.031590909

17.5	56.06308598	1.031162791

20	55.28602742	1.030714286

22.5	54.51891525	1.030243902

25	53.7620806	1.02975

27.5	53.01586474	1.029230769

30	52.28061906	1.028684211

32.5	51.55670517	1.028108108

35	50.84449475	1.0275

37.5	50.14436954	1.026857143

40	49.45672111	1.026176471

42.5	48.78195074	1.025454545

45	48.12046904	1.0246875

47.5	47.4726957	1.023870968

50	46.83905899	1.023

52.5	46.21999524	1.022068966

55	45.61594831	1.021071429

57.5	45.02736878	1.02

60	44.45471322	1.018846154

62.5	43.89844326	1.0176

65	43.35902455	1.01625

67.5	42.83692562	1.014782609

70	42.33261666	1.013181818

72.5	41.84656813	1.011428571

75	41.37924925	1.0095

77.5	40.93112648	1.007368421

80	40.50266173	1.005

82.5	40.09431064	1.002352941

85	39.70652064	0.999375

87.5	39.33972898	0.996

90	38.99436075	0.992142857

92.5	38.67082672	0.987692308

95	38.3695213	0.9825

97.5	38.09082036	0.976363636

100	37.83507916	0.969

102.5	37.60263028	0.96

105	37.3937816	0.94875

107.5	37.20881436	0.934285714

110	37.04798141	0.915

112.5	36.9115055	0.888

115	36.79957782	0.8475

117.5	36.71235664	0.78

120	36.64996625	0.645

122.5	36.61249606	0.24

125	36.6	0.24

127.5	36.61220718	0.237938144

130	36.64589883	0.237826087

132.5	36.6949721	0.237701149

135	36.75396376	0.237560976

137.5	36.81920808	0.237402597

140	36.88846925	0.237222222

142.5	36.96039863	0.237014925

145	37.03416464	0.236774194

147.5	37.10923758	0.236491228

150	37.18526839	0.236153846

152.5	37.26201957	0.235744681

155	37.33932479	0.235238095

157.5	37.41706451	0.234594595

160	37.49515085	0.23375

162.5	37.57351785	0.232592593

165	37.65211516	0.230909091

167.5	37.73090367	0.228235294

170	37.80985258	0.223333333

172.5	37.88893734	0.211428571

175	37.96813811	0.2

176	37.99984718	0.2

[rrathishubham]

Note: Cooling tower starts from a height of 9.17m from ground as columns has a height of 9.17m 

height
from ground (m)
radius (m)
thickness (m)



9.17
58.71998481
1.05



10
58.45077875
1.044153913



12.5
57.64576787
1.032



15
56.84976984
1.031590909



17.5
56.06308598
1.031162791



20
55.28602742
1.030714286



22.5
54.51891525
1.030243902



25
53.7620806
1.02975



27.5
53.01586474
1.029230769



30
52.28061906
1.028684211



32.5
51.55670517
1.028108108



35
50.84449475
1.0275



37.5
50.14436954
1.026857143



40
49.45672111
1.026176471



42.5
48.78195074
1.025454545



45
48.12046904
1.0246875



47.5
47.4726957
1.023870968



50
46.83905899
1.023



52.5
46.21999524
1.022068966



55
45.61594831
1.021071429



57.5
45.02736878
1.02



60
44.45471322
1.018846154



62.5
43.89844326
1.0176



65
43.35902455
1.01625



67.5
42.83692562
1.014782609



70
42.33261666
1.013181818



72.5
41.84656813
1.011428571



75
41.37924925
1.0095



77.5
40.93112648
1.007368421



80
40.50266173
1.005



82.5
40.09431064
1.002352941



85
39.70652064
0.999375



87.5
39.33972898
0.996



90
38.99436075
0.992142857



92.5
38.67082672
0.987692308



95
38.3695213
0.9825



97.5
38.09082036
0.976363636



100
37.83507916
0.969



102.5
37.60263028
0.96



105
37.3937816
0.94875



107.5
37.20881436
0.934285714



110
37.04798141
0.915



112.5
36.9115055
0.888



115
36.79957782
0.8475



117.5
36.71235664
0.78



120
36.64996625
0.645



122.5
36.61249606
0.24



125
36.6
0.24



127.5
36.61220718
0.237938144



130
36.64589883
0.237826087



132.5
36.6949721
0.237701149



135
36.75396376
0.237560976



137.5
36.81920808
0.237402597



140
36.88846925
0.237222222



142.5
36.96039863
0.237014925



145
37.03416464
0.236774194



147.5
37.10923758
0.236491228



150
37.18526839
0.236153846



152.5
37.26201957
0.235744681



155
37.33932479
0.235238095



157.5
37.41706451
0.234594595



160
37.49515085
0.23375



162.5
37.57351785
0.232592593



165
37.65211516
0.230909091



167.5
37.73090367
0.228235294



170
37.80985258
0.223333333



172.5
37.88893734
0.211428571



175
37.96813811
0.2



176
37.99984718
0.2

[peteroznewman]

What version of ANSYS are you using:  18.2  19.2  other?

[rrathishubham]

I'm using version 18.1

[peteroznewman]

Here is the plan. Take the spreadsheet and make two tabs, one for the inner surface, one for the outer surface. On the tab for the inner surface, delete the Thickness column. Cut the Radius column and paste it in front of the Height column. Now the first column is the X coordinate, the second column is the Y coordinate. Fill the third column with 0.0 for the Z coordinate.

On the second tab, in the fourth column, add the radius to the thickness to make the Y coordinate of the outer surface. Cut that column and Paste Special (Values) in front of column A to be the X coordinate. The height is the Y coordinate and insert a column of 0.0 for the Z coordinate. Delete the other rows.

Next you have to format those two tabs into the 3D Curve data format that DesignModeler requires.

Once you have a text file with the data in the correct format, you start a new Workbench file. RMB on the Geometry cell and get the Properties.  You must set the Analysis Type to 2D before you open DesignModeler.

In DesignModeler, Concept, 3D Curve. Definition > From Coordinates File. Then pick the inner surface file.  Repeat for the outer surface file.

Finally, make a sketch that uses those two 3D curves and two lines to close off the cross-sectional surface that is the geometry that can be meshed to perform an axisymmetric model.

Alternatively, you could put the inner and outer coordinates in one file and define a closed 3D line and you wouldn't have to sketch the two lines.

[rrathishubham]

Thankyou so much for your reply. I'll revert back once i create the geometry. Once again thankyou sir, thanks a lot.

[rrathishubham]

Sir, I was able to import the file and it created the curve as I wanted but could you please tell me that how do I create closed geometry? I even read the link you provided but I didn't understand that what should be the format for closed geometry and in the last row where shall I put 1 and 0 to close geometry.

[peteroznewman]

Forget about the closed curve.

You can have four groups in a single text file.

Group 1 can be the inner curve from the bottom to the top.

Group 2 can be from the inner top to the outer top (two points).

Group 3 can be the outer curve from top to bottom (reverse sort the height).

Group 4 can be from the outer bottom to the inner bottom (two points).

I think you will be able to select these four curves to make a surface.

[rrathishubham]

Sir, I made the geometry using 4 groups and later using "Surface from Edges", I created surface. Is it correct? And once I take the geometry into mechanical tab, I cant see any option to revolve the geometry.

[rrathishubham]

Also, can i put reinforcement in 2D model? Or do I need to model it in 3D? If I can put the reinforcement in 2D model, then how can I put?

[rrathishubham]

Sir, I have revolved the geometry in mechanical tab. Also I have meshed it. Could just tell me about the reinforcement?

[peteroznewman]

A 2D axisymmetric model is used to calculate and visualize the stress and strain on a 2D radial slice of a 3D rotationally symmetric object. The surface you created from the four curves is that radial slice. The surface is what you mesh. You also have to support and load the structure. I suggest a fixed support for the bottom edge and Standard Earth Gravity in the -Y direction. By default, all models begin with Structural Steel. If you want to use a different material, you have to create that in Engineering Data, and then you have to assign that to the surface in Mechanical. Then you can solve and look at results. There is a way to display the results from the surface by revolving the results around the axis to display the results in 3D.

Reinforcement is done in 3D. It doesn't make sense in 2D except for a hoop that goes around the axis. You can't have any axial reinforcements that are only every 20 degrees because that is not axisymmetric.

I recommend you get results from a 2D axisymmetric model of an unreinforced material before you venture into 3D models.

Once you have 2D results, you can mark this discussion with Is Solution and open a New Discussion for questions on reinforcements in 3D models.

[rrathishubham]

Okay sir... And yes, the slice from 4 curves is radial slice. I'll try to do it without reinforcement.