{"id":32340,"date":"2018-12-27T12:15:59","date_gmt":"2018-12-27T12:15:59","guid":{"rendered":"\/forum\/forums\/topic\/dynamic-mesh-negative-cell-volume\/"},"modified":"2018-12-27T12:15:59","modified_gmt":"2018-12-27T12:15:59","slug":"dynamic-mesh-negative-cell-volume","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/dynamic-mesh-negative-cell-volume\/","title":{"rendered":"Dynamic Mesh &#8211; Negative Cell Volume"},"content":{"rendered":"<p>Hi,<\/p>\n<p><\/p>\n<p>I&acute;m trying to simulate the movement of the piston in white. Triangle elements for the mesh (size 1e-4m). UDF function for the velocity (v=0.075*cos(30*time)) and an amplitude of 5mm for the movement.<\/p>\n<p><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/d652d665-7f9c-42a4-8f4c-a96d00d34316\/94a23720-3173-49fd-a6d2-a9c300ca105f_1.jpg?width=690&amp;upscale=false\" alt=\"\"><\/p>\n<p><\/p>\n<p>Below the setup for the dynamic mesh (Piston as Rigid Body &#8211; Interior as Deforming and Wall_Piston as Stationary).<\/p>\n<p><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/d652d665-7f9c-42a4-8f4c-a96d00d34316\/fc22970d-02f3-4256-8452-a9c300ca4846_5.jpg?width=690&amp;upscale=false\" alt=\"\" width=\"438\" height=\"455\"> <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/d652d665-7f9c-42a4-8f4c-a96d00d34316\/ea09b0d1-3c54-47ec-9c68-a9c300ca54a7_7.jpg?width=690&amp;upscale=false\" alt=\"\" width=\"275\" height=\"458\"><\/p>\n<p><\/p>\n<p>When I display the mesh motion, I have not straight lines which move with the piston, and when I remove &#8220;Wall_Piston as Stationary&#8221;, it disappears.<\/p>\n<p><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/d652d665-7f9c-42a4-8f4c-a96d00d34316\/ce755d7f-f122-4869-a5c9-a9c300caf622_3.jpg?width=690&amp;upscale=false\" alt=\"\" width=\"547\" height=\"328\"><\/p>\n<p><\/p>\n<p>Problem is when I try to preview the mesh motion (delta t=1E-3= max velocity \/ minimum cell size), I have this message.<\/p>\n<p><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/d652d665-7f9c-42a4-8f4c-a96d00d34316\/a3bc1f55-7758-41f3-93c0-a9c300cb75a6_4.jpg?width=690&amp;upscale=false\" alt=\"\"><\/p>\n<p><\/p>\n<p>What Type should I choose for the &#8220;Wall_piston&#8221;? I have try with Deforming and a cylinder as Definition but it doesn&acute;t run. I have also delete the interior as Deforming. <\/p>\n<p><\/p>\n<p>&nbsp;<\/p>\n<p><\/p>\n<p>Regards,<\/p>\n<p><\/p>\n<p>Maxime<\/p>\n","protected":false},"template":"","class_list":["post-32340","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_old_topic_id":["4512"],"_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":["2179"],"_bbp_subscription":["237203"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["32340"],"_bbp_forum_id":["27792"],"_bbp_engagement":["62","199","159144"],"_bbp_voice_count":["3"],"_bbp_reply_count":["11"],"_bbp_last_reply_id":["73836"],"_bbp_last_active_id":["73836"],"_bbp_last_active_time":["2019-01-04 14:06:37"]},"test":"max4"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/32340","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\/32340\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=32340"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}