<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 21 Mar 2018, at 09:49, Yangxin He <<a href="mailto:y67he@uwaterloo.ca" class="">y67he@uwaterloo.ca</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div id="divtagdefaultwrapper" dir="ltr" style="font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; font-size: 12pt; font-family: Calibri, Helvetica, sans-serif;" class=""><div style="margin-top: 0px; margin-bottom: 0px;" class="">Hi Jody,</div><div style="margin-top: 0px; margin-bottom: 0px;" class=""><br class=""></div><div style="margin-top: 0px; margin-bottom: 0px;" class="">Sorry, I wasn't clear. Yes, I did mean a mode-1 internal tide coded in obcs_calc.F.</div><div style="margin-top: 0px; margin-bottom: 0px;" class="">For the obcs_sponge.F, I deleted the part that has the western/left boundary sponge, so this way I only have sponge on the eastern/right boundary.</div><div style="margin-top: 0px; margin-bottom: 0px;" class=""><br class=""></div><div style="margin-top: 0px; margin-bottom: 0px;" class="">I see in your data.obcs, you only got 10 points in the sponge. thats amazing. I am gonna try a much smaller time scale and 100 sponge points to see what happens.</div><div style="margin-top: 0px; margin-bottom: 0px;" class="">If this doesn't work, I will try reducing the the grid size in the sponge. Just to clarify, I can read in a grid with stretched grid sizes near the right boundary and I don't need another package to do this, right?</div></div></div></blockquote><div><br class=""></div><div>Well, be a little careful, that setup has the sponge turned off. But yes, I do get away with 10-15 points or so because my sponge ends up > 300 km because I’ve really stretched those distant points. You need to do the grid stretching slowly so there aren’t any reflections from gridsize mismatches. I think I do something like 1%-2% stretching rate (i.e. dxnext = dxprev * 1.01). Much of this happens before the sponge.</div><div><br class=""></div><div>Cheers, Jody </div><div><br class=""></div><div><br class=""></div><br class=""><blockquote type="cite" class=""><div class=""><div id="divtagdefaultwrapper" dir="ltr" style="font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; font-size: 12pt; font-family: Calibri, Helvetica, sans-serif;" class=""><div style="margin-top: 0px; margin-bottom: 0px;" class=""><br class=""></div><div style="margin-top: 0px; margin-bottom: 0px;" class="">Thanks</div><div style="margin-top: 0px; margin-bottom: 0px;" class=""><br class=""></div><div style="margin-top: 0px; margin-bottom: 0px;" class="">Yangxin</div></div><hr tabindex="-1" style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; display: inline-block; width: 537.03125px;" class=""><span style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class=""></span><div id="divRplyFwdMsg" dir="ltr" style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><font face="Calibri, sans-serif" style="font-size: 11pt;" class=""><b class="">From:</b><span class="Apple-converted-space"> </span>MITgcm-support <<a href="mailto:mitgcm-support-bounces@mitgcm.org" class="">mitgcm-support-bounces@mitgcm.org</a>> on behalf of Jody Klymak <<a href="mailto:jklymak@uvic.ca" class="">jklymak@uvic.ca</a>><br class=""><b class="">Sent:</b><span class="Apple-converted-space"> </span>Wednesday, March 21, 2018 12:35:09 PM<br class=""><b class="">To:</b><span class="Apple-converted-space"> </span><a href="mailto:mitgcm-support@mitgcm.org" class="">mitgcm-support@mitgcm.org</a><br class=""><b class="">Subject:</b><span class="Apple-converted-space"> </span>Re: [MITgcm-support] parameters in obcs sponge layer</font><div class=""> </div></div><div style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">Dear Yangxin,<div class=""><br class=""></div><div class="">Something like that should work. Not sure what you mean by “internal waves”, but if you mean you force a mode-1 wave, you can do that via calculation in `obcs_calc.F`, but note that will apply *one* value of the boundary condition through the sponge. Your sponge is 400-km long, so the wave won’t be very freely propagating. For those sorts of problems, I suggest using `rbcs` package, and set the problem up with your ideal wave having spatial and temporal structure, so the wave is “freely” propagating through the incoming sponge. You can find an example of this at <a href="https://github.com/jklymak/TwoDMode1Reflect" class="">https://github.com/jklymak/TwoDMode1Reflect</a></div><div class=""><br class=""></div><div class="">For the absorbing sponge, it seems to me your timescales are far too long to absorb fast mode-1 waves. </div><div class=""><br class=""></div><div class="">For these sorts of problems, I always stretch the grid near the bdys and far from my region of interest. You don’t need a lot of resolution in the sponge region, so if you make it quite large it usually does a good job of absorbing everything.</div><div class=""><br class=""></div><div class="">Cheers, Jody</div><div class=""><br class=""><div class=""><br class=""><blockquote type="cite" class=""><div class="">On 21 Mar 2018, at 09:09, Yangxin He <<a href="mailto:y67he@uwaterloo.ca" class="">y67he@uwaterloo.ca</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div id="divtagdefaultwrapper" dir="ltr" class="" style="font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; font-size: 12pt; font-family: Calibri, Helvetica, sans-serif;"><div class="" style="margin-top: 0px; margin-bottom: 0px;">Hey there,</div><div class="" style="margin-top: 0px; margin-bottom: 0px;"><br class=""></div><div class="" style="margin-top: 0px; margin-bottom: 0px;">Here is my toy problem,</div><div class="" style="margin-top: 0px; margin-bottom: 0px;">I have no slip at the bottom, rigid lid at the top, I am sending internal waves of M2 tidal frequency using obcs_calc.F from the left boundary with max(U)=0.02 m/s, I want to impose a sponge layer using orcs_sponge.F on the right boundary. </div><div class="" style="margin-top: 0px; margin-bottom: 0px;">1 grid cell in the y-direction, i.e. it is a 2d simulation.</div><div class="" style="margin-top: 0px; margin-bottom: 0px;">50 points vertically with a uniform gird size of 40m.</div><div class="" style="margin-top: 0px; margin-bottom: 0px;">2000 points horizontally with a uniform gird size of 500m.</div><div class="" style="margin-top: 0px; margin-bottom: 0px;">An example of my data.obcs file looks like:</div><div class="" style="margin: 0px; font-stretch: normal; font-size: 12px; line-height: normal; font-family: Courier; color: rgb(255, 240, 165); background-color: rgb(19, 119, 61);"><span class="" style="font-variant-ligatures: no-common-ligatures;"># Open-boundaries</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 12px; line-height: normal; font-family: Courier; color: rgb(255, 240, 165); background-color: rgb(19, 119, 61);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> &OBCS_PARM01</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 12px; line-height: normal; font-family: Courier; color: rgb(255, 240, 165); background-color: rgb(19, 119, 61);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> OB_Ieast=-1,</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 12px; line-height: normal; font-family: Courier; color: rgb(255, 240, 165); background-color: rgb(19, 119, 61);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> OB_Iwest=1,</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 12px; line-height: normal; font-family: Courier; color: rgb(255, 240, 165); background-color: rgb(19, 119, 61);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> useOBCSsponge=.TRUE.,</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 12px; line-height: normal; font-family: Courier; color: rgb(255, 240, 165); background-color: rgb(19, 119, 61);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> &</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 12px; line-height: normal; font-family: Courier; color: rgb(255, 240, 165); background-color: rgb(19, 119, 61);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> &OBCS_PARM03</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 12px; line-height: normal; font-family: Courier; color: rgb(255, 240, 165); background-color: rgb(19, 119, 61);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> spongeThickness=800,</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 12px; line-height: normal; font-family: Courier; color: rgb(255, 240, 165); background-color: rgb(19, 119, 61);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> Urelaxobcsinner=89424.,</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 12px; line-height: normal; font-family: Courier; color: rgb(255, 240, 165); background-color: rgb(19, 119, 61);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> Vrelaxobcsinner=89424.,</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 12px; line-height: normal; font-family: Courier; color: rgb(255, 240, 165); background-color: rgb(19, 119, 61);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> Urelaxobcsbound=4471.,</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 12px; line-height: normal; font-family: Courier; color: rgb(255, 240, 165); background-color: rgb(19, 119, 61);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> Vrelaxobcsbound=4471.,</span></div><p class="" style="margin-top: 0px; margin-bottom: 0px;"></p><div class="" style="margin: 0px; font-stretch: normal; font-size: 12px; line-height: normal; font-family: Courier; color: rgb(255, 240, 165); background-color: rgb(19, 119, 61);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> &</span></div><div class="" style="margin-top: 0px; margin-bottom: 0px;">What I want to achieve is this sponge layer shall work well so that all waves are being absorbed, no reflections back and it should work even after 30 or 40 tidal periods or even longer.<br class=""></div><div class="" style="margin-top: 0px; margin-bottom: 0px;">I have tried various values for the five parameters listed in &OBCS_PARM3, following the basic principle, </div><div class="" style="margin-top: 0px; margin-bottom: 0px;">1) a fairly large U/Vrelaxobcsinner to make sure the forcing is small when the waves hit the sponge.</div><div class="" style="margin-top: 0px; margin-bottom: 0px;">2) a fairly small U/Vrelaxobcsbound to make sure the forcing is still large enough so the waves can be fully absorbed.</div><div class="" style="margin-top: 0px; margin-bottom: 0px;">1) the thicker the sponge layer is, the better it shall work.</div><div class="" style="margin-top: 0px; margin-bottom: 0px;">The problem is none of the parameters I tried worked.</div><div class="" style="margin-top: 0px; margin-bottom: 0px;"><br class=""></div><div class="" style="margin-top: 0px; margin-bottom: 0px;">I assume somebody must have done similar work as this one. I would really appreciate some insights as to what values I shall assign those parameters.</div><div class="" style="margin-top: 0px; margin-bottom: 0px;"><br class=""></div><div class="" style="margin-top: 0px; margin-bottom: 0px;">Thanks</div><div class="" style="margin-top: 0px; margin-bottom: 0px;"><br class=""></div><div class="" style="margin-top: 0px; margin-bottom: 0px;">Yangxin</div><div class="" style="margin: 0px; font-stretch: normal; font-size: 12px; line-height: normal; font-family: Courier; color: rgb(255, 240, 165); background-color: rgb(19, 119, 61);"><br class=""></div><p class="" style="margin: 0px; font-stretch: normal; font-size: 12px; line-height: normal; font-family: Courier; color: rgb(255, 240, 165); background-color: rgb(19, 119, 61);"><span class="" style="font-variant-ligatures: no-common-ligatures;"></span></p></div><span class="" style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">_______________________________________________</span><br class="" style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span class="" style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">MITgcm-support mailing list</span><br class="" style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><a href="mailto:MITgcm-support@mitgcm.org" class="" style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;">MITgcm-support@mitgcm.org</a><br class="" style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><a href="http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support" class="" style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;">http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support</a></div></blockquote></div><br class=""><div class=""><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px; font-family: "Lucida Sans Typewriter"; font-size: 12px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-east-asian: normal; font-variant-position: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-indent: 0px; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px;"><div class="" style="word-wrap: break-word;"><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px; font-family: "Lucida Sans Typewriter"; font-size: 12px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-east-asian: normal; font-variant-position: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-indent: 0px; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px;"><div class="">--</div><div class="">Jody Klymak </div><div class=""><a href="http://web.uvic.ca/~jklymak/" class="">http://web.uvic.ca/~jklymak/</a></div><div class=""><br class="khtml-block-placeholder"></div><div class=""><br class="khtml-block-placeholder"></div><br class="Apple-interchange-newline"></span></div></span><br class="Apple-interchange-newline"></div><br class=""></div></div><span style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">_______________________________________________</span><br style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">MITgcm-support mailing list</span><br style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class=""><a href="mailto:MITgcm-support@mitgcm.org" class="">MITgcm-support@mitgcm.org</a></span><br style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: LucidaSans-Typewriter; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class=""><a href="http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support" class="">http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support</a></span></div></blockquote></div><br class=""><div class="">
<span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px; color: rgb(0, 0, 0); font-family: 'Lucida Sans Typewriter'; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-indent: 0px; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px;"><div style="word-wrap: break-word;" class=""><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px; color: rgb(0, 0, 0); font-family: 'Lucida Sans Typewriter'; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-indent: 0px; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px;"><div class="">--</div><div class="">Jody Klymak </div><div class=""><a href="http://web.uvic.ca/~jklymak/" class="">http://web.uvic.ca/~jklymak/</a></div><div class=""><br class="khtml-block-placeholder"></div><div class=""><br class="khtml-block-placeholder"></div><br class="Apple-interchange-newline"></span></div></span><br class="Apple-interchange-newline">
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