Chemical reaction fronts separate regions of reacted and unreacted substances as they propagate in liquids. These fronts may induce density gradients due to different chemical compositions and temperatures across the front. In this paper, we investigate buoyancy-induced convection driven by both types of gradients. We consider a thin front approximation where the normal front velocity depends only on the front curvature. This model applies for small curvature fronts independent of the specific type of chemical reaction. For density changes due only to heat variations near the front, we find that convection can take place for either upward or downward propagating fronts if density gradients are above a threshold. Convection can set in even if the fluid with lower density is above the higher density fluid. Our model consists of Navier-Stokes equations coupled to the front propagation equation. We carry out a linear stability analysis to determine the parameters for the onset of convection. We study the nonlinear front propagation for liquids confined in narrow two-dimensional domains. Convection leads to fronts of steady shape, propagating with constant velocities.

中文翻译：

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薄反应前沿中的热和成分驱动的对流

当反应物质在液体中传播时，化学反应前沿将已反应物质和未反应物质的区域分开。由于锋面的化学成分和温度不同，这些锋面可能会引起密度梯度。在本文中，我们研究了两种梯度驱动的浮力引起的对流。我们考虑薄前沿近似，其中法向前沿速度仅取决于前沿曲率。该模型适用于小曲率前沿，与具体的化学反应类型无关。对于仅由于锋面附近的热量变化而引起的密度变化，我们发现如果密度梯度高于阈值，则向上或向下传播的锋面都会发生对流。即使密度较低的流体位于密度较高的流体上方，也会产生对流。我们的模型由与前沿传播方程耦合的纳维-斯托克斯方程组成。我们进行线性稳定性分析以确定对流开始的参数。我们研究狭窄二维域内液体的非线性前向传播。对流导致锋面形状稳定，并以恒定的速度传播。