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<div style="margin-top:0;margin-bottom:0;">Hi Adam,</div>
<div style="margin-top:0;margin-bottom:0;">Thank you very much. <br>
</div>
<div style="margin-top:0;margin-bottom:0;">Actually, my work requires the system to be in a stationary state. For that, there is a need for me to add some internal energy removing mechanism in order to maintain the steady state, as has been done in
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<div style="margin-top:0;margin-bottom:0;">J. Wang, L.-P. Wang, Z. Xiao, Y. Shi, and S. Chen, A hybrid numerical simulation of isotropic compressible</div>
<div style="margin-top:0;margin-bottom:0;"> </div>
<div>turbulence, J. Comp. Phys. 229, 5257 (2010).</div>
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<div style="margin-top:0;margin-bottom:0;"> </div>
<div style="margin-top:0;margin-bottom:0;">Please refer to page 38. The energy removal has also been done in my more studies.</div>
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<div style="margin-top:0;margin-bottom:0;">As I am new to Flash, could you please help me in adding the energy removing term.<br>
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<div style="margin-top:0;margin-bottom:0;">Thank you</div>
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<div style="margin-top:0;margin-bottom:0;">Best regards,</div>
<div style="margin-top:0;margin-bottom:0;">Shadab</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Reyes, Adam <adam.reyes@rochester.edu><br>
<b>Sent:</b> Friday, May 10, 2024 12:50:38 PM<br>
<b>To:</b> Alam Shadab TU Ilmenau<br>
<b>Cc:</b> flash-users@flash.rochester.edu<br>
<b>Subject:</b> Re: [FLASH-USERS] Internal energy is not reaching statistical steady state in StirTurb (homogeneous isotropic turbulence) problem</font>
<div> </div>
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<div>Hi Shadab,
<div><br>
</div>
<div>The stirring is injecting kinetic energy into the simulation constantly throughout the simulation. This gets dissipated to internal energy through viscosity and has nowhere to go with a periodic box. <br id="lineBreakAtBeginningOfMessage">
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*********************************************<br>
Adam Reyes</div>
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<blockquote type="cite">
<div>On May 10, 2024, at 12:42 PM, Alam Shadab TU Ilmenau <shadab.alam@tu-ilmenau.de> wrote:</div>
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<div id="divtagdefaultwrapper" dir="ltr" style="font-style: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; text-decoration: none; font-size: 12pt; font-family: Calibri, Helvetica, sans-serif, "EmojiFont", "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols;">
<div style="margin-top:0px; margin-bottom:0px">Hi,</div>
<div style="margin-top:0px; margin-bottom:0px">I am simulating<span class="Apple-converted-space"> </span><span>homogeneous isotropic turbulence</span><span class="Apple-converted-space"> </span>with stir forcing. I am facing a challenge that the internal energy
is not reaching to statistical steady state no matter how small the energy supply rate is. On the other hand, the kinetic energy has reached steady state. Following are the plots of these quantities:</div>
<div style="margin-top:0px; margin-bottom:0px"><span id="cid:1093ed08-0703-4a08-9f51-5f31c6f9b1b1"><int_energy.png></span><br>
<span id="cid:35aff225-b892-48f8-ab54-2fb0a75bf7a8"><kinetic_energy.png></span><br>
input parameters for this run are:<span class="Apple-converted-space"> </span><br>
</div>
<div style="margin-top:0px; margin-bottom:0px">energy input - 1e-4 per mode (around 100 modes are stirred)</div>
<div style="margin-top:0px; margin-bottom:0px">kinematic viscosity: 0.1</div>
<div style="margin-top:0px; margin-bottom:0px">diffusivity: 0.1</div>
<div style="margin-top:0px; margin-bottom:0px">grid: 128^3</div>
<div style="margin-top:0px; margin-bottom:0px"><br>
</div>
<div style="margin-top:0px; margin-bottom:0px">I simulated the Stirturb problem for many other input parameters using split and unsplit methods, but I am getting the similar trend for the energies.</div>
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<div style="margin-top:0px; margin-bottom:0px">What am I missing because of which the internal energy is keep on increasing? Could anyone please help me with this?</div>
<div style="margin-top:0px; margin-bottom:0px"><br>
</div>
<div style="margin-top:0px; margin-bottom:0px">Best regards,</div>
<div style="margin-top:0px; margin-bottom:0px">Shadab</div>
<div style="margin-top:0px; margin-bottom:0px">T<span><span>echnische Universität Ilmenau, Germany</span></span><br>
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