Based on the lattice Boltzmann (LB) method, pore-scale simulations are performed to investigate the differential diffusion effects on the density-driven instability (DI) with chemical reaction $A+B\to C$ in {porous media. A partially miscible stratification is considered, and thus only solutes from the top fluid can diffuse down into the host fluid in pore spaces.} Tests with different values of the Rayleigh number ${\mathrm{\text{Ra}}}_r$ and the diffusion coefficient $D_r$ of species $r$ ($r=A,B,C$) are considered. The results demonstrate eight distinct scenarios of DI, and four of them are not observed in equal diffusivity simulations. Two differential diffusion effects, namely, the double-diffusive (DD) and the diffusive-layer convection (DLC) mechanisms, can act upon the gravity field and give rise to new fingering phenomena. DD mechanism comes into play and results in a local minimum density layer if ${\mathrm{\text{Ra}}}_B/{\mathrm{\text{Ra}}}_C$ is small and $D_B>D_C$; and DLC becomes significant and brings in a local maximum density layer if ${\mathrm{\text{Ra}}}_B/{\mathrm{\text{Ra}}}_C$ is large and $D_B

中文翻译：

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差分扩散对多孔介质中反应流密度驱动的不稳定性的影响

基于晶格玻尔兹曼（LB）方法，进行了孔尺度模拟，研究了化学反应对微分扩散对密度驱动的不稳定性（DI）的影响。 $\mathrm{一种}+乙\to C$在{多孔介质中。考虑到部分可混溶的分层，因此只有顶部流体中的溶质才能向下扩散到孔隙空间中的主体流体中。}使用不同的瑞利数值进行测试${\mathrm{\text{镭}}}_{\mathrm{[R}}$ 和扩散系数 $d_{\mathrm{[R}}$ 种类 $\mathrm{[R}$ （$\mathrm{[R}=\mathrm{一种}，乙，C$） 被考虑。结果证明了8种不同的DI情况，而在相同的扩散率模拟中未观察到其中4种。两种不同的扩散效应，即双扩散（DD）和扩散层对流（DLC）机制，可以作用于重力场并产生新的指法现象。DD机制发挥作用，并在以下情况下导致局部最小密度层${\mathrm{\text{镭}}}_{乙}/{\mathrm{\text{镭}}}_C$ 小而 $d_{乙}>d_C$; DLC变得很重要，并且在以下情况下引入了局部最大密度层${\mathrm{\text{镭}}}_{乙}/{\mathrm{\text{镭}}}_C$ 大且$ D_B