{"id":32149,"date":"2018-12-14T12:04:48","date_gmt":"2018-12-14T12:04:48","guid":{"rendered":"\/forum\/forums\/topic\/boundary-layer-thickness-along-a-line\/"},"modified":"2018-12-14T12:04:48","modified_gmt":"2018-12-14T12:04:48","slug":"boundary-layer-thickness-along-a-line","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/boundary-layer-thickness-along-a-line\/","title":{"rendered":"Boundary Layer Thickness along a line"},"content":{"rendered":"

Hello Ansys-Community,<\/p>\n

<\/p>\n

i have a problem and would be really happy if someone can help me. I already searched for a solution but couldn’t find anything.<\/p>\n

<\/p>\n

I have simulated a nozzle with a convergent and divergent part. I want to compute the boundary layer thickness (BLT) along the wall (X-axis) with 99 % of the maximum velocity-magnitude. The contour of the wall isn’t parallel to the axis of the nozzle. So I am going to create lines which stand normal to the wall\/symmetry-axis. I can determine the position of the 99% maximum velocity-magnitude on the created line. The position is the curve length along the corresponding line which starts with zero on the wall (Y-axis) and ends on the symmetry-axis. The direction of the Y-axis depends on the line because the Y-axis is parallel to the lines; it means one time it stays normal to the X-axis and one time to the symmetry-axis. On the next step I want to compare the BLT on both lines (normal to the wall\/symmetry-axis on the same starting point on the wall); see screenshot.<\/p>\n

<\/p>\n

However, i need to create manually lines, searching for the maximum speed on the corresponding line and compute the 99% of the maximum speed to get the boundary layer thickness (BLT). I need many lines because the BLT can change within a short x-Distance strongly due to the shockwave. It is very time-consuming to do this work manually.<\/p>\n

<\/p>\n

My solution:<\/span>
Create lines (perpendicular to the wall and\/or sym-axis) with parameters in journal-file or UserDefinedFunctions (UDF). But in Fluent and CFD-Post is no possibility to put parameters in the option “create line”. This Option wants just points.
I would start with a parameter like 0.1 and go in 0.01 steps until I reach the X-position on the wall at 0.3 to create automatically many lines. The next step should be writing a script like:
“Compute the position of the 99% maximum speed on the corresponding line. Create a *.txt-file with values for the X-axis on the wall and the BLT for the Y-axis (see diagram in violet in the screenshot).”<\/p>\n

<\/p>\n

So I want a plot like the violet diagram in the screenshot with values:<\/p>\n

<\/p>\n

X-axis (wall)<\/span>   BLT<\/span><\/p>\n

<\/p>\n

0.1                  0.002
0.11                0.0023
0.12                0.000001       (maybe here shockwave)
…                     …
0.3                  0.05
END<\/p>\n

<\/p>\n

This work should be work automatically and I tried many things like iso-surface and so on. The problem on an iso-surface is that the maximum of velocity on a corresponding line depends to the line. And the maximum is not every time on the “free steam” position; so not every time on the symmetry axis.<\/p>\n

<\/p>\n

I hope I could explain my problem and hope we can find a clever solution. Thank you in advance.<\/p>\n

<\/p>\n

Best regards
Mustafa<\/p>\n

<\/p>\n

 \"\"<\/p>\n","protected":false},"template":"","class_list":["post-32149","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_old_topic_id":["4321"],"_bbp_old_topic_author_name_id":["Anonymous"],"_bbp_old_is_topic_anonymous_id":["false"],"_bbp_old_closed_status_id":["publish"],"_bbp_author_ip":[null],"_bbp_old_sticky_status_id":["normal"],"_bbp_likes_count":["0","0","0","0","0"],"_btv_view_count":["3415"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["32149"],"_bbp_forum_id":["27792"],"_bbp_engagement":["22555","161163"],"_bbp_voice_count":["2"],"_bbp_reply_count":["6"],"_bbp_last_reply_id":["72869"],"_bbp_last_active_id":["72869"],"_bbp_last_active_time":["2018-12-19 16:40:46"]},"test":"muchanical"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/32149","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/32149\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=32149"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}