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Hello
I am using Blue kenue to build my mesh. However I have read that I need to have a well-oriented mesh and domain area. My domain area is in Mercator projection therefore, I would like to know how can I oriented my domain in Blue kenue in order to add the following commands words in my steering file. (LATITUDE OF ORIGIN POINT and LONGITUDE OF ORIGIN POINT) because as far as Understood the projection is supposed to be done around this point, but how can I do that?

I know that I need to include that words with the coordinates of my reference point in my steering file but my questions is related to how can I do that in Blue Kenue. or Is there another way to shifted the domain area based on a reference point?

Note: I have tried the function "Shift XY" in BK. However I did not work.

For example I want the reference point at
X = -111.902617 Longitude West
Y = 23.107399 Latitude North (Near to the Gulf of California entrance)

Equal in Mercator as:

X_Mercator = -12456942.331691
Y_Mercator = 2628249.228182

Thank you
Joel

Hello

I'm not sure that I've understood your post! But why want you to convert latiutde/longitude to x/y ? Telemac can do it for you !
You have to build you mesh with BK in long/lat coordinates and then tell to telemac that you are using SPATIAL PROJECTION TYPE=3. Otherwise use SPATIAL PROJECTION TYPE=2 if you have already x/y coordinates with Mercator projection.

with my kind regards
Riadh

Hello Riadh

Thank you very much for your reply.
With regards to my question I would like to run the simulation in Mercator However I need to well-oriented my mesh based on a reference point that I already have choose. So that I need to know how can I shifted the domain area relating to that point.

I am using in my steering file
LATITUDE OF ORIGIN POINT = 23.107399
LONGITUDE OF ORIGIN POINT) = -111.902617

But I need to refer my domain area into this reference point. I used shifted function in BK but It did not work.

Thank you
Joel

Hello Joel

I don't understand this " I need to well-oriented my mesh based on a reference point that I already have choose.".
Who told you that you need to change orientation ? I'm not expert in projection but I think that there is no need to change any orientation in the mesh.

with my best regards
Riadh

Hi
I think there is different problems here.
The conversion between long/lat and Mercator is not simply a shift in X/Y.

So you should first clarify how you built your mesh, in which coordinate system ...

About the orientation of the mesh, I suppose you mean orientation of the triangles. This is not modified by a coordinate change so if you produce a good mesh in BK in sens of well oriented element (counter clockwise), it still a well oriented mesh after mesh transformation.

Hope this helps

Hello

I would like to clarify my problem

I am using Mercator projection to run my simulation in Telemac 2D but as far I understood I need to allocate my domain area based on a reference point I already selected as

I am using in my steering file
LATITUDE OF ORIGIN POINT = 23.107399
LONGITUDE OF ORIGIN POINT) = -111.902617

Equal in Mercator as:

X_Mercator = -12456942.331691
Y_Mercator = 2628249.228182

However I can I allocate my mesh domain based on this point.

I converted lat lon coordinates to Mercator then I open the domain area in BK to created my mesh. But I would like to refer my domain area with the point I choose.

Thank you and I am sorry for the misunderstanding.
Joel

Hello Riadh

I had followed your recommendation to run the simulation in lat long however a message appeared on telemac that I need to convert the lat long in radians. That's why I wanted to keep working with Mercator otherwise I need to change all my files to radians because it is not easy to use lat long as you mentioned below.

This was the message

LATITUDE MUST BE GIVEN IN RADIANS
HERE Y(I)= 33.670173645019531 FOR I= 1
USE CORRXY (BIEF) FOR CONVERSION


Therefore I would like to keep working in Mercator projection because I already have all my files in Mercator. So that I would like to know how can I specify or shift the domain area based on a reference point as I tried to explain you before.

Thank you
Joel

Hello Joel

first, you can use corxy to convert x and y like it is said in the message (if you want to go on with lat/long)

Otherwise if you come back to mercator, you do not need to use any modification to your coordinates since Mercator projection, does not need any changes. If you use spherical coodinates only, you need to introduce a original point.

Please have a look on subroutine inbief.f (in sources/utils/bief) to understand how Telemac manages the coodinates in case of Mercator or spherical coodinates case.

I'm not sure that I've answered to yours questions, but I hope that this helps anyway

with my kind regards

Riadh

Hello Riadh
Thank you for your answer.

I think you mentioned my problem in your response. In order to introduce a original point I have used the words

LATITUDE OF ORIGIN POINT = 23.107399
LONGITUDE OF ORIGIN POINT) = -111.902617

However, If I will not modified the domain area within this coordinates as a reference point, my results simulation seems like I am in a different region. So that my question is How can I change the domain area I choose for my simulation according to the origin point. Attached you can see the results simulation that are completely out of my domain area.

Hello Joel

Try to add the following keywords:

GEOGRAPHIC SYSTEM =5
ZONE NUMBER IN GEOGRAPHIC SYSTEM = it seems to be 12 (verify it)

I hope this helps
with my kind regards

Riadh