We investigate the miscible displacement of a viscous liquid by a less viscous one in a porous medium, which frequently leads to the formation of a mixing zone characterized by thin fingers. The mixing zone grows in time due to the difference in speed between the leading and trailing edges. The transverse flow equilibrium (TFE) model provides estimates of these speeds. We propose an enhancement for the TFE estimates. It is based on the assumption that an intermediate concentration exists near the tip of the finger, which allows to reduce the integration interval in the speed estimate. Numerical simulations of the computational fluid dynamics model were conducted to validate the new estimates. The refined estimates offer greater accuracy than those provided by the original TFE model.

翻译：我们研究了多孔介质中低粘度液体驱替高粘度液体的混溶驱替过程，该过程常导致形成具有细长指状特征的混合区。由于前缘与后缘的速度差异，混合区随时间增长。横向流平衡（TFE）模型提供了这些速度的估算方法。我们提出了一种改进TFE估算的方法，其依据是假设指端附近存在中间浓度，从而能够缩小速度估算中的积分区间。通过计算流体动力学模型的数值模拟验证了新的估算方法。改进后的估算方法比原始TFE模型具有更高的精度。