[t_shirt]

Hi All,

I just have two question;
how can we create 2D blade airfoil outer boundary as shown in attached pic?

Basically it is a periodic boundary is there any mathematical relation or equations if yes pls let me know where i can get it?

I am using ICEM CFD, what will be step i will follow to create for meshing here?

Thank you and Regards,

[PSYMN]

As a starting point, I usually draw a curve from the stagnation point thru midpoints along the blade all the way to the tip. This is my initial shape. Then I copy that up (or down) by half the blade spacing. Then I add a tangential curve from the inlet plane to the front of the curve and a second one from the trailing edge to the outlet plane.

But in the end, I usually just let the smoother move those sides. The solver doesn't really care about the shape or location of those periodic curves (but the spacing is important). The smoother will move those nodes to optimize quality and maintain periodicity.

[Saima]

Hi PSYMN,

I am writing script for ICEM CFD. Some where in my geometry i split edge at a point, but when i am writing script it takes as a coordinate like:

ic_hex_split_edge 55 43 0 1.68349 8.84739 0


Instead of taking coordiante i want to assign a point i have a point on the same position like pnt.06 at (x,y,z): (1.68349, 8.84739, 0)

but i dont know how i can write it in this line.

Kindly let me know. I will be greatfull of u.


Thank you

Originally Posted by PSYMN

As a starting point, I usually draw a curve from the stagnation point thru midpoints along the blade all the way to the tip. This is my initial shape. Then I copy that up (or down) by half the blade spacing. Then I add a tangential curve from the inlet plane to the front of the curve and a second one from the trailing edge to the outlet plane.

But in the end, I usually just let the smoother move those sides. The solver doesn't really care about the shape or location of those periodic curves (but the spacing is important). The smoother will move those nodes to optimize quality and maintain periodicity.

[PSYMN]

Hey Samia,

You are using the wrong command...

Under Split Edge, you will see a "Split Method" option. The default methid is "Screen Select" which uses an XYZ location. Even if you use it to select a point, it really just gives the location of the point (as you saw).

However, if you choose the "Prescribed point" Split Method, it will use the point name (which is what you want because it is much more parametric).
SplitBlock_PrescribedPoint.gif


The command should look something like this...

ic_hex_split_grid 22 38 PointName.21 m POINTS CURVES SURFS SOLID

[Saima]

Thank you PSYMN,

Actualy if u see this you tube web site for airfoil http://www.youtube.com/watch?v=EknKV...eature=related

Here instead of using "Automatic Linear" option under edit edge command for overlaping block+airfoil wall, i am using linear or spline option. That command generates it.

I dont know why automatic linear option does not working in my case.

Kindly suggest me the way make it automatic or atleast give point at this stage.

Regards,

Originally Posted by PSYMN

Hey Samia,

You are using the wrong command...

Under Split Edge, you will see a "Split Method" option. The default methid is "Screen Select" which uses an XYZ location. Even if you use it to select a point, it really just gives the location of the point (as you saw).

However, if you choose the "Prescribed point" Split Method, it will use the point name (which is what you want because it is much more parametric).
Attachment 4078


The command should look something like this...

ic_hex_split_grid 22 38 PointName.21 m POINTS CURVES SURFS SOLID

[PSYMN]

Oops, sorry, i read it too quickly and thought you meant split block. Split edge doesn't have a point selection option (although it does say to select a point, I will fix that...)

What you would need to do is use a command like ic_geo_pick_location... (you can look it up int he programmers guide, you would need to actually type it into the replay script) This would give you output in terms of x, y, z for a particular point name, then you would set those to $X, $Y, and $Z which you would use in the split edge line...

We could discuss that more if that is what you really want to do...

However, if you just want to split automatic like I did... That uses the Edge distribution to determine the linear edge split locations. If it is not working for you, it is probably because you have not set your edge parameters so your edge only has nodes on either end and there are no locations for the automatic split edge to use...

Simon

[Saima]

Hi PSYMN,

Thank you for reply.
But i am still not able to do command which told me.
I have commands in script file, after using Block----edit edge----split type....Method:linear

ic_hex_split_edge 53 41 0 0.52817 7.82042 0
ic_hex_split_edge 55 43 0 1.68349 8.84739 0
ic_hex_split_edge 49 55 0 3.24686 7.10986 0
ic_hex_split_edge 47 53 0 1.83217 6.03755 0

Now i want to edit my script in the manner it picks point name instead of coordinate like:

ic_hex_split_edge 53 41 0 pnt06
since pnt 06: 0.52817 7.82042 0

But this is not working. I tried urs one after giving
ic_geo_pick_location 0.52817 7.82042 0

it give me error does not recognized "0".

I tried with $ too but it is not working and secondly how it know i am picking location for spliting edges 53 and 41.

I am waiting for your reply.

Thank you




but my script is not working

Originally Posted by PSYMN

Oops, sorry, i read it too quickly and thought you meant split block. Split edge doesn't have a point selection option (although it does say to select a point, I will fix that...)

What you would need to do is use a command like ic_geo_pick_location... (you can look it up int he programmers guide, you would need to actually type it into the replay script) This would give you output in terms of x, y, z for a particular point name, then you would set those to $X, $Y, and $Z which you would use in the split edge line...

We could discuss that more if that is what you really want to do...

However, if you just want to split automatic like I did... That uses the Edge distribution to determine the linear edge split locations. If it is not working for you, it is probably because you have not set your edge parameters so your edge only has nodes on either end and there are no locations for the automatic split edge to use...

Simon

[PSYMN]

Samia, you took me completely backwards...

the pick location should be applied against the point name (not the location). That would then give the location that you could use in the actual command (with the $x, $y, $z)...

Try inserting something like this for each split edge command... (example script supplied to me by Jari)

set name pnt.00 ;# point must exist
set loc [ic_geo_get_point_location $name]
set x [lindex $loc 0]
set y [lindex $loc 1]
set z [lindex $loc 2]
ic_hex_split_edge 21 25 0 $x $y $z

Hope that helps.

Also, you asked about the number 0 after the two vertex numbers (e.g. edge 21 25 0). This means that it is between vertex 21 (start vertex) and 25 (end vertex). "0" is the first split, if the number were 1, it would mean that this split is the second between the vertex 21 and vertex 25.

I am not sure why this wasn't included in the Programmers guide. I will ask them to fix that.

[Saima]

Thank you so much Simon.

It is working well. I really appreciated.

Best Regards,
Saima

Originally Posted by PSYMN

Samia, you took me completely backwards...

the pick location should be applied against the point name (not the location). That would then give the location that you could use in the actual command (with the $x, $y, $z)...

Try inserting something like this for each split edge command... (example script supplied to me by Jari)

set name pnt.00 ;# point must exist
set loc [ic_geo_get_point_location $name]
set x [lindex $loc 0]
set y [lindex $loc 1]
set z [lindex $loc 2]
ic_hex_split_edge 21 25 0 $x $y $z

Hope that helps.

Also, you asked about the number 0 after the two vertex numbers (e.g. edge 21 25 0). This means that it is between vertex 21 (start vertex) and 25 (end vertex). "0" is the first split, if the number were 1, it would mean that this split is the second between the vertex 21 and vertex 25.

I am not sure why this wasn't included in the Programmers guide. I will ask them to fix that.

[venkat_aero2007]

Originally Posted by PSYMN

As a starting point, I usually draw a curve from the stagnation point thru midpoints along the blade all the way to the tip. This is my initial shape. Then I copy that up (or down) by half the blade spacing. Then I add a tangential curve from the inlet plane to the front of the curve and a second one from the trailing edge to the outlet plane.

But in the end, I usually just let the smoother move those sides. The solver doesn't really care about the shape or location of those periodic curves (but the spacing is important). The smoother will move those nodes to optimize quality and maintain periodicity.

Hi Simon,

I have created the Periodic boundary curve (Figure 1) as explained in your post. But I dont know to make it as smooth curve (Figure2). Could you please suggest me some idea to get a smooth periodic curve.

Regards,
Venkat

[Far]

Draw few points on one of the periodic curve and then join them with nurbs option. Delete the original curve and copy newly create curve to other periodic location. Done

[venkat_aero2007]

Hi Far,

Thanks for your reply. I am not able to find Nurbs option in ICEM CFD. Do you mean spline option.

[Far]

Yes. It is

[venkat_aero2007]

Once again thanks Far