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.

不稳定的多孔介质流动建立了重要的流动现象。有许多技术应用和环境流问题，其中流动不稳定，例如在大气边界层中流过植物檐篷，并在水下波的影响下或湍流边界层的相互作用与土壤上层或雪层上层的流动和运输的相互作用。在生物体中，血液和质量运输的流量也可以视为通过多孔培养基的不稳定流动。到目前为止，在文献中找不到对这些不稳定流问题的独特描述和建模，以及关于如何治疗它们的不同概念，在大多数情况下，在代表性基本体积（REV）的规模上描述了多孔介质中的流量。在此规模上，有必要通过合适的模型对流与固体之间的相互作用进行建模。众所周知的Darcy和Forchheimer方程在多孔介质中被广泛接受，尽管系数在很大程度上取决于流量状态。在不稳定的流动中，稳态相互作用模型无法在不稳定的流动过程中强烈变化。对于线性状态中不稳定流动的流动（RE << 1），申请人能够证明，动能的音量平均方程式可以纠正不稳定的Darcy方程中的时间常数，该方程与孔隙空间中Navier-Stokes方程式完全解决的解决方案非常吻合。该建议的目标是该建议的目标。我们打算在压力梯度和振荡流的阶段变化后研究瞬态流动。将使用我们自己的Navier-Stokes求解器进行完全分辨的孔隙空间中的直接数值模拟。我们计划在二维几何形状（圆柱体包）和三维几何形状（球形包）中进行模拟。我们的兴趣是对相互作用项，耗散和时间常数的宏观建模。在不稳定的多孔介质流中，将特别关注从线性到非线性以及从非线性到湍流状态的过渡。