Hi Jacques, Thanks for your response. One more question. Is there dual-time stepping method in Nektar++? Best, Chengeng Jacques Xing <jacques.xing@kcl.ac.uk> 于2023年3月10日周五 16:51写道：

Hi Chengeng,

In CFD, local time stepping means that each element is updated from the local value of the time step computed from the specified CFL number. Local time stepping is used to accelerate convergence to the steady state solution as each element is updated by different value of time step, the solution obtained is not time-accurate (unless combined with an approach such as dual-time stepping).

Best, Jacques ------------------------------ *From:* nektar-users-bounces@imperial.ac.uk < nektar-users-bounces@imperial.ac.uk> on behalf of Chengeng Qian < qiancg0313@gmail.com> *Sent:* Friday, March 10, 2023 8:15 AM *To:* nektar-users@imperial.ac.uk <nektar-users@imperial.ac.uk> *Subject:* [Nektar-users] Parameters for local time stepping

Some people who received this message don't often get email from qiancg0313@gmail.com. Learn why this is important <https://aka.ms/LearnAboutSenderIdentification>

This email from qiancg0313@gmail.com originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list <https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fspam.ic.ac.uk%2FSpamConsole%2FSenders.aspx&data=05%7C01%7Cjacques.xing%40kcl.ac.uk%7Cc50c3f71b79a4c11ccc408db213fbc48%7C8370cf1416f34c16b83c724071654356%7C0%7C0%7C638140329844370704%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=6CrH8zNb7NfQMbhsXsSNz2YJWoaCYgHwyqBWenW4iwY%3D&reserved=0> to disable email stamping for this address.

Hi everyone, What is following parameter used for?

<I PROPERTY="LocalTimeStep" VALUE="True" />

I though that it must be ture if we calculated time step using CFL. But I found that I could run case with LocalTimeStep = False. In addition, the result obtained by LocalTimeStep = Ture is more closed to the steady solution. Any comments are appreciated.

Cheers, Chengeng.

Hi Jacques, OK, I see. Many thanks for your kind response. Best, Chengeng Jacques Xing <jacques.xing@kcl.ac.uk> 于2023年3月10日周五 19:00写道：

Hi Chengeng,

As far as I know, there is no dual time stepping approach implemented in Nektar++.

Best, Jacques ------------------------------ *From:* Chengeng Qian <qiancg0313@gmail.com> *Sent:* Friday, March 10, 2023 9:56 AM *To:* Jacques Xing <jacques.xing@kcl.ac.uk> *Cc:* nektar-users@imperial.ac.uk <nektar-users@imperial.ac.uk> *Subject:* Re: [Nektar-users] Parameters for local time stepping

You don't often get email from qiancg0313@gmail.com. Learn why this is important <https://aka.ms/LearnAboutSenderIdentification> Hi Jacques, Thanks for your response. One more question. Is there dual-time stepping method in Nektar++?

Best, Chengeng

Jacques Xing <jacques.xing@kcl.ac.uk> 于2023年3月10日周五 16:51写道：

Hi Chengeng,

In CFD, local time stepping means that each element is updated from the local value of the time step computed from the specified CFL number. Local time stepping is used to accelerate convergence to the steady state solution as each element is updated by different value of time step, the solution obtained is not time-accurate (unless combined with an approach such as dual-time stepping).

Best, Jacques ------------------------------ *From:* nektar-users-bounces@imperial.ac.uk < nektar-users-bounces@imperial.ac.uk> on behalf of Chengeng Qian < qiancg0313@gmail.com> *Sent:* Friday, March 10, 2023 8:15 AM *To:* nektar-users@imperial.ac.uk <nektar-users@imperial.ac.uk> *Subject:* [Nektar-users] Parameters for local time stepping

Some people who received this message don't often get email from qiancg0313@gmail.com. Learn why this is important <https://aka.ms/LearnAboutSenderIdentification>

This email from qiancg0313@gmail.com originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list <https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fspam.ic.ac.uk%2FSpamConsole%2FSenders.aspx&data=05%7C01%7Cjacques.xing%40kcl.ac.uk%7Cd7246ebbfca143db1cb208db214dcda0%7C8370cf1416f34c16b83c724071654356%7C0%7C0%7C638140390257391053%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=%2Fs3JUMSgT2vyWmGHwGl652LKFnBo%2BgR8wriWNXcezIo%3D&reserved=0> to disable email stamping for this address.

Hi everyone, What is following parameter used for?

<I PROPERTY="LocalTimeStep" VALUE="True" />

I though that it must be ture if we calculated time step using CFL. But I found that I could run case with LocalTimeStep = False. In addition, the result obtained by LocalTimeStep = Ture is more closed to the steady solution. Any comments are appreciated.

Cheers, Chengeng.