{"id":277901,"date":"2023-04-04T22:35:40","date_gmt":"2023-04-04T22:35:40","guid":{"rendered":"\/forum\/forums\/topic\/time-step-size-for-acoustic-simulation\/"},"modified":"2023-04-04T22:35:40","modified_gmt":"2023-04-04T22:35:40","slug":"time-step-size-for-acoustic-simulation","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/time-step-size-for-acoustic-simulation\/","title":{"rendered":"Time step size for Acoustic Simulation"},"content":{"rendered":"<p>Hello,<\/p>\n<p>I&#8217;m calculating acoustic pressure inside pipe using LES+Ffowcs Willams and Hawkings (FW-H) model.&nbsp;<\/p>\n<p>During the calcualtion, I noticed that the results extremly depend on the time stpe size. I tried that time step size 5E-5, 1.1E-6 and 5E-7 sec. And the result is the figure below. The time step size is smaller, the peaks shift to right. I calculated this result by the steps;<\/p>\n<p style=\"padding-left: 40px\">1) ANSYS fluent calcuates acoustics pressure with LES+FW-H model<\/p>\n<p style=\"padding-left: 40px\">2)Power spectral density (psd) is calculated from the acoustic pressure<\/p>\n<p style=\"padding-left: 40px\">3)spl = dB(sqrt(psd*df))<\/p>\n<p>Do you have any idea why the peak of the sound pressure level shift to large when the time step size becomes small?<\/p>\n<p>And how much should I decrease the time step size?<\/p>\n<p>Thanks!<\/p>\n<p>&nbsp;<img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/04\/04-04-2023-1680647037-mceclip0.png\" width=\"362\" height=\"302\"><\/p>\n","protected":false},"template":"","class_list":["post-277901","topic","type-topic","status-closed","hentry","topic-tag-acoustic-1","topic-tag-acousticsimulation-1","topic-tag-ffowcs-william-hawkings-2"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["264444","13659"],"_bbp_author_ip":["23.192.164.18"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["959"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["277901"],"_bbp_forum_id":["27792"],"_bbp_engagement":["13659","264444"],"_bbp_voice_count":["2"],"_bbp_reply_count":["1"],"_bbp_last_reply_id":["277972"],"_bbp_last_active_id":["277972"],"_bbp_last_active_time":["2023-04-05 12:25:51"]},"test":"hamanaka-ytamu-edu"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/277901","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\/277901\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=277901"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}