Simulation, analysis and modeling of unsteady flow in porous media

多孔介质中非定常流动的模拟、分析和建模

• 批准号: 276859331
• 负责人: Professor Dr.-Ing. Michael Manhart
• 金额: --
• 依托单位: Professur für Hydromechanik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/276859331?language=en
• 关键词: Simulation; analysis; modeling; unsteady; flow

Unsteady porous media flow establish an important class of flow phenomena. There is a number of technical applications and environmental flow problems in which the flow is unsteady, e.g. flows through plant canopies in atmospheric boundary layers and under the influence of waves underwater or the interaction of a turbulent boundary layer flow with the flow and transport in the upper layer of the soil or a snow layer. The flow of blood and mass transport in living organisms can as well be considered as unsteady flow through porous media. So far, a unique description and modeling of these unsteady flow problems can not be found in the literature and different concepts on how to treat them exist.In most cases, flows in porous media are described on the scale of a representative elementary volume (REV). On this scale it is necessary to model the interaction between flow and solid by suitable models. The well known Darcy and Forchheimer equations are widely accepted for steady flows in porous media, although the coefficients depend strongly on the flow state. In unsteady flows, the steady-state interaction models can not be used as they strongly vary during unsteady flow. For unsteady flow in the linear regime (Re<<1), the applicant was able to demonstrate that the volume averaged equation for the kinetic energy provides a correction to the time constant in the unsteady Darcy equation that agrees well with fully resolved solutions of Navier-Stokes equations in the pore space.The goal of this proposal is to analyze unsteady flow in porous media in the non-linear and turbulent regime. We intend to study transient flow after a step change in pressure gradient and oscillatory flow. A direct numerical simulation in fully resolved pore space will be undertaken using our own Navier-Stokes solver. We plan to do simulations in two-dimensional geometries (cylinder packs) and three-dimensional geometries (sphere packs). Our interest is on macroscopic modeling of interaction terms, dissipation and time constant in unsteady porous media flow. A special focus will be on the transition from linear to non-linear and from non-linear to turbulent states in unsteady porous media flow.

非稳定渗流是一类重要的渗流现象。有许多技术应用和环境流动问题，其中流动是不稳定的，例如在大气边界层中和在水下波浪的影响下通过植物冠层的流动，或者湍流边界层流与土壤或雪层的上层中的流动和运输的相互作用。生物体内的血液流动和物质输运也可以看作是通过多孔介质的不稳定流动。到目前为止，在文献中还没有找到对这些非定常流动问题的唯一描述和建模，并且在如何处理它们的问题上存在不同的概念。在这个尺度上，有必要通过合适的模型来模拟流动和固体之间的相互作用。众所周知的达西和Forchheimer方程被广泛接受的多孔介质中的稳定流动，虽然系数强烈地依赖于流动状态。在非定常流动中，由于定常干扰模型在非定常流动中变化很大，因此不能使用定常干扰模型。对于线性区域（Re<<1）中的非稳态流，申请人能够证明，用于动能的体积平均方程提供了对非稳态达西方程中的时间常数的校正，其与孔隙空间中的Navier-Stokes方程的完全解析解非常一致。我们打算研究压力梯度阶跃变化后的瞬态流动和振荡流动。将采用我们自己的Navier-Stokes解算器进行完全解析孔隙空间的直接数值模拟。我们计划在二维几何（圆柱包）和三维几何（球包）中进行模拟。我们的兴趣是在非稳态多孔介质流的相互作用项，耗散和时间常数的宏观模拟。一个特别的重点将是从线性过渡到非线性和从非线性到湍流状态的非定常多孔介质流。