{"id":360352,"date":"2024-04-03T17:00:02","date_gmt":"2024-04-03T17:00:02","guid":{"rendered":"\/forum\/forums\/reply\/360352\/"},"modified":"2024-04-03T17:05:56","modified_gmt":"2024-04-03T17:05:56","slug":"360352","status":"publish","type":"reply","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/360352\/","title":{"rendered":"Reply To: Velocity of a bullet fired in open air\/atmosphere."},"content":{"rendered":"

<p><span style=”font-size: 12pt;”>Hello Venkatesh,<\/span><\/p><p><span style=”font-size: 12pt;”>Could you clarify more about the problem you are trying to model? As far as I can understand, you are prescribing motions at the back surface of the bullet and expecting it to drop down after some time – the part I don’t understand is that why it has to drop down if there is no external force or friction acting upon it!<\/span><\/p><p><span style=”font-size: 12pt;”>If you’re trying to understand the behavior of a bullet due to gravity load, then model the bullet as a rigid body (if we don’t care about the deformations it’ll have during the flight) and apply the gravity in the Z direction using *LOAD_BODY_Z. For more information you can take a look here: https:\/\/www.dynasupport.com\/howtos\/general\/gravity-load<\/a>.<\/span><\/p><p><span style=”font-size: 12pt;”>However, (though unrealistic) if you want to understand the behavior of the bullet under the friction of the atmosphere then I believe, you’d need to do a CFD analysis. I’m not an expert about it but I think, you can do some research about achieving this using ALE or SPH element. To know about the intricacies to perform it using LS-Dyna, you can find some useful conference articles in here: https:\/\/www.dynalook.com<\/a>\/. I think initially starting from a “ballistic protection” will be much easier as previously people used Dyna a lot to do this kind of simulations. One person who did a lot of these kinds of simulations that I can think of is Varmint Al, an ex scientist and engineer of LLNL. A massive collection of his experience with these type of modeling and Dyna are available in his website: https:\/\/www.varmintal.com\/aengr.htm<\/a>.<\/span><\/p><p><span style=”font-size: 12pt;”>I hope these suggestions will help to answer your question to some extent. Happy modeling. Thanks!<\/span><\/p><p> <\/p><p><span style=”font-size: 12pt;”>- Tonmoy.<\/span><\/p><\/p>\n","protected":false},"template":"","class_list":["post-360352","reply","type-reply","status-publish","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t