Density‐dependent flow and transport solutions for coastal saltwater intrusion investigations, analyses of fluid injection into deep brines, and studies of convective fingering and instabilities of denser fluids moving through less dense fluids typically formulate the groundwater flow equation in terms of pressure or equivalent freshwater head. A formulation of the flow equation in terms of hydraulic head is presented here as an alternative. The hydraulic‐head formulation can facilitate adaptation of existing constant‐density groundwater flow codes to include density‐driven flow by avoiding the need to convert between freshwater head and hydraulic head within the code and by incorporating density‐dependent terms as a compartmentalized “correction” to constant‐density calculations already performed by the code. The hydraulic‐head formulation also accommodates complexities such as unconfined groundwater flow and Newton‐Raphson solution schemes more readily than the freshwater‐head formulation. Simulation results are presented for four example problems solved using an implementation of the hydraulic‐head formulation in MODFLOW.

中文翻译：

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液压头配方，用于密度依赖的流量和运输

用于沿海咸水入侵调查，对深层盐水注入流体的分析以及对流指法和密度较大的流体在密度较小的流体中流动的不稳定性的研究的密度依赖的流量和运输解决方案通常用压力或等效淡水头的形式来表示地下水流量方程。作为替代方案，此处介绍了根据液压头的流量方程式。液压头公式可通过避免在规范内的淡水头和液压头之间进行转换以及将依赖于密度的术语作为分隔的“校正”来促进对现有恒定密度地下水流规则的适应，以包括密度驱动的流量。到代码已经执行的恒定密度计算。与淡水头公式相比，液压头公式还可以适应复杂的情况，例如无限制的地下水流量和Newton-Raphson解决方案。给出了四个示例问题的仿真结果，这些问题是通过在MODFLOW中实施液压头公式解决的。