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Pustam | पुस्तम | পুস্তম🇳🇵<p>Convection–diffusion equation<br />The convection-diffusion equation is a more general version of the scalar transport equation. It is a combination of the diffusion and convection (advection) equations. It describes physical phenomena where particles, energy, or other physical quantities are transferred inside a physical system due to two processes: diffusion and convection.<br />\[\dfrac{\partial c}{\partial t} = \mathbf{\nabla} \cdot (D \mathbf{\nabla} c - \mathbf{v} c) + R\]</p><p>\[\dfrac{\partial c}{\partial t} = \underbrace{\mathbf{\nabla} \cdot (D \mathbf{\nabla} c)}_{\text{diffusion}}-\overbrace{\underbrace{\mathbf{\nabla}\cdot (\mathbf{v} c)}_{\text{advection}}}^\text{convection} + \overbrace{\underbrace{R}_\text{destruction}}^\text{creation}\] </p><p>\(\mathbf{\nabla} \cdot (D \mathbf{\nabla} c)\) is the contribution of diffusion.<br />\(- \mathbf{\nabla}\cdot (\mathbf{v} c)\) is the contribution of convection or advection.<br />\(R\) describes the creation or destruction of the quantity.</p><p>where<br />\(c\) is the variable of interest.<br />\(D\) is the diffusivity.<br />\(\mathbf{v}\) is the velocity field, and<br />\(R\) is the sources or sinks of the quantity \(c\).</p><p><a href="https://mathstodon.xyz/tags/Convection" class="mention hashtag" rel="tag">#<span>Convection</span></a> <a href="https://mathstodon.xyz/tags/Diffusion" class="mention hashtag" rel="tag">#<span>Diffusion</span></a> <a href="https://mathstodon.xyz/tags/Transport" class="mention hashtag" rel="tag">#<span>Transport</span></a> <a href="https://mathstodon.xyz/tags/Advection" class="mention hashtag" rel="tag">#<span>Advection</span></a> <a href="https://mathstodon.xyz/tags/Equation" class="mention hashtag" rel="tag">#<span>Equation</span></a> <a href="https://mathstodon.xyz/tags/ConvectionDiffusionEquation" class="mention hashtag" rel="tag">#<span>ConvectionDiffusionEquation</span></a> <a href="https://mathstodon.xyz/tags/DifferentialEquations" class="mention hashtag" rel="tag">#<span>DifferentialEquations</span></a> <a href="https://mathstodon.xyz/tags/AdvectionEquation" class="mention hashtag" rel="tag">#<span>AdvectionEquation</span></a> <a href="https://mathstodon.xyz/tags/DiffusionEquation" class="mention hashtag" rel="tag">#<span>DiffusionEquation</span></a> <a href="https://mathstodon.xyz/tags/TransportEquation" class="mention hashtag" rel="tag">#<span>TransportEquation</span></a> <a href="https://mathstodon.xyz/tags/ConvectionEquation" class="mention hashtag" rel="tag">#<span>ConvectionEquation</span></a></p>
Lukasz Kaczmarczyk<p>An example of an error indicator is driven non-conforming mesh adaptivity for <a href="https://fosstodon.org/tags/advection" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>advection</span></a> problem using upwind high order <a href="https://fosstodon.org/tags/DG" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>DG</span></a>. Wind velocity is discretised by vector potential function in H1 one space. <a href="https://fosstodon.org/tags/MOFEM" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MOFEM</span></a> can do very cool things. That technology is implemented for 2d/3d problems. <a href="https://fosstodon.org/tags/FEM" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>FEM</span></a> <a href="https://fosstodon.org/tags/FEA" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>FEA</span></a> <a href="https://fosstodon.org/tags/HPC" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>HPC</span></a> </p><p>Example <a href="https://fosstodon.org/tags/code" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>code</span></a> is here:<br><a href="http://mofem.eng.gla.ac.uk/mofem/html/tutorial_level_set.html" rel="nofollow noopener noreferrer" target="_blank"><span class="invisible">http://</span><span class="ellipsis">mofem.eng.gla.ac.uk/mofem/html</span><span class="invisible">/tutorial_level_set.html</span></a></p>
Fernando Racimo<p>Our new paper on modelling the <a href="https://fediscience.org/tags/spatiotemporal" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>spatiotemporal</span></a> dynamics of a beneficial genetic variant is out <span class="h-card"><a href="https://fediscience.org/@eLife" class="u-url mention" rel="nofollow noopener noreferrer" target="_blank">@<span>eLife</span></a></span>.<br>Muktupavela et al: <a href="https://elifesciences.org/articles/73767" rel="nofollow noopener noreferrer" target="_blank"><span class="invisible">https://</span><span class="ellipsis">elifesciences.org/articles/737</span><span class="invisible">67</span></a><br>Plus a digest highlight here: <a href="https://elifesciences.org/digests/73767/evolving-through-time-and-space" rel="nofollow noopener noreferrer" target="_blank"><span class="invisible">https://</span><span class="ellipsis">elifesciences.org/digests/7376</span><span class="invisible">7/evolving-through-time-and-space</span></a></p><p>We extend a <a href="https://fediscience.org/tags/diffusion" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>diffusion</span></a> method for inferring the spread of a strongly selected allele, originally developed by Novembre et al. (<a href="https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.0030339" rel="nofollow noopener noreferrer" target="_blank"><span class="invisible">https://</span><span class="ellipsis">journals.plos.org/plosbiology/</span><span class="invisible">article?id=10.1371/journal.pbio.0030339</span></a>). We now incorporate <a href="https://fediscience.org/tags/ancientDNA" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>ancientDNA</span></a> and allow for <a href="https://fediscience.org/tags/advection" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>advection</span></a> dynamics.</p><p><a href="https://fediscience.org/tags/EvolutionaryGenetics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>EvolutionaryGenetics</span></a> <a href="https://fediscience.org/tags/Evolution" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Evolution</span></a> <a href="https://fediscience.org/tags/Genetics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Genetics</span></a> <a href="https://fediscience.org/tags/EcoEvo" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>EcoEvo</span></a> <a href="https://fediscience.org/tags/archaeology" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>archaeology</span></a> <a href="https://fediscience.org/tags/HumanEvolution" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>HumanEvolution</span></a></p>
Prof. Tatiana Ilyina<p><span class="h-card"><a href="https://wisskomm.social/@MPI_Meteo" class="u-url mention" rel="nofollow noopener noreferrer" target="_blank">@<span>MPI_Meteo</span></a></span> </p><p>The most computationally expensive part of such models is the transport (by <a href="https://mas.to/tags/advection" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>advection</span></a> and <a href="https://mas.to/tags/diffusion" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>diffusion</span></a>) of <a href="https://mas.to/tags/biogeochemical" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>biogeochemical</span></a> <a href="https://mas.to/tags/tracers" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>tracers</span></a> (zoo and <a href="https://mas.to/tags/phytoplankton" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>phytoplankton</span></a> <a href="https://mas.to/tags/nutrients" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>nutrients</span></a>, organic and inorganic <a href="https://mas.to/tags/carbon" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>carbon</span></a>, etc) with the <a href="https://mas.to/tags/ocean" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>ocean</span></a> <a href="https://mas.to/tags/flow" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>flow</span></a>.</p><p>The more tracers we include to represent the complexity of <a href="https://mas.to/tags/ocean" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>ocean</span></a> biogeochemistry, the slower are the model runs. Same problem arises when the <a href="https://mas.to/tags/spatial" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>spatial</span></a> <a href="https://mas.to/tags/resolution" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>resolution</span></a> of an <a href="https://mas.to/tags/ESM" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>ESM</span></a> increases.</p><p>Biogeochemistry models can become a bottleneck in <a href="https://mas.to/tags/ESM" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>ESM</span></a> computations. 2/</p>