{"id":36237,"date":"2019-06-28T14:35:36","date_gmt":"2019-06-28T14:35:36","guid":{"rendered":"\/forum\/forums\/topic\/heave-and-pitch-motions-of-a-high-speed-planing-hull-using-fluent\/"},"modified":"2019-06-28T14:35:36","modified_gmt":"2019-06-28T14:35:36","slug":"heave-and-pitch-motions-of-a-high-speed-planing-hull-using-fluent","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/heave-and-pitch-motions-of-a-high-speed-planing-hull-using-fluent\/","title":{"rendered":"heave and pitch motions of a high speed planing hull using Fluent"},"content":{"rendered":"

Hello, <\/p>\n

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I k   I know this has been raised several times but I reached a point where I couldn’t go on anymore. I’m trying to simulate the motion of a planing hull through regular head sea waves in order to predict the heave and pitch motions. I keep getting negative cell volume error after 600 or more iterations (depending on my time step size). The geometry created is for half a hull from the transverse section. I will start from the mesh. my mesh is shown in the following figure:<\/p>\n

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Min orthogonal quality is 0.2524
Max skewness = 0.7986
Number of elements=1587073
Nodes= 279232<\/p>\n

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I created a body of influence at the water level to enhance the mesh. the mesh quality check is shown in the following pic:<\/p>\n

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My setup is created as follows:<\/p>\n

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1. VOF multi-phase with K-Omega SST viscous as shown below:<\/p>\n

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Two phase material created with primary as air and secondary as water.<\/p>\n

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My user defined function is as follows:<\/p>\n

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my dynamic mesh setup is as follows:<\/p>\n

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I have tried several setups here like diffusion, I also changed the spring constant factor to 1 or 0 but no hope.<\/p>\n

I defined three dynamic mesh zones as follows:<\/p>\n

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1. Hull as rigid body with 6dof on ( tried to put solution stabilisation with scale factor 0.2 method: coefficient-based).
2. interiof fluid as rigid body  with 6dof and passive on.
3. symmetry_inside face as deforming (shown in the following pic)<\/p>\n

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boundary conditions as follows:<\/p>\n

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I was confused what to choose for free surface and bottom level but then i understood that free surface is water level which is in my case the point of origin of the coordinate system and bottom is the bottom of the domain which is 4 m below the origin in the y axis. <\/p>\n

outlet conditions are as follows:<\/p>\n

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the hull is a wall and the rest of the surfaces are symmetry.<\/p>\n

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solution method is as follows:
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I tried other options with no hope.<\/p>\n

I tried several time step size from 0.01 to 0.0001 with no hope. <\/p>\n

Could you please let me know whats wrong with my simulation? <\/p>\n

I read that I could define the moving mesh zones as user defined, could you please let me know how ?<\/p>\n

Many thanks in advance.<\/p>\n

<\/p>\n","protected":false},"template":"","class_list":["post-36237","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_old_topic_id":["8409"],"_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"],"_btv_view_count":["955"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["36237"],"_bbp_forum_id":["27792"],"_bbp_engagement":["62","199","163443","163874"],"_bbp_voice_count":["4"],"_bbp_reply_count":["6"],"_bbp_last_reply_id":["107735"],"_bbp_last_active_id":["107735"],"_bbp_last_active_time":["2020-03-13 05:11:09"]},"test":"jafar"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/36237","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\/36237\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=36237"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}