Direct numerical simulation of turbulent channel flow over porous walls
Direct numerical simulation of turbulent channel flow over porous walls
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DOI：
10.1017/jfm.2015.566
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发表时间：
2014-10
影响因子：
3.7
通讯作者：
M. Rosti;L. Cortelezzi;M. Quadrio
中科院分区：
文献类型：
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作者：
M. Rosti;L. Cortelezzi;M. Quadrio
我们进行直接数值模拟（DNS）的湍流通道流多孔壁。在流体区域中的流动是由不可压缩的Navier-Stokes（NS）方程，而在多孔层的体积平均Navier-Stokes（VANS）方程，这是通过体积平均的微观流场超过一个小的体积，大于典型的尺寸的孔隙。通过这种方式，多孔介质具有连续描述，并且可以通过独立分配渗透率和孔隙度来指定，而不需要详细了解孔隙微观结构。在多孔材料和流体区域之间的界面处，施加动量传递条件，其中与界面的未知结构相关的可用系数可以用作误差估计。为了建立数值问题，耦合NS和VANS方程的速度-涡度公式推导并在伪谱DNS求解器中实现。大多数的模拟进行在$Re_{\it\tau}}=180$，并考虑低渗透率的材料，参数研究是用来描述所发挥的作用，渗透率，孔隙度，多孔材料的厚度，和系数的动量传递界面条件。其中渗透率，即使是非常小的，显示发挥了重要的作用，在确定的通道流的可渗透壁的响应。湍流统计和瞬时流场，在一个光滑的不可渗透的墙壁上的流动的比较形式，被用来了解多孔材料引入的主要变化。在较高雷诺数的模拟被用来说明的主要标度量。
We perform direct numerical simulations (DNS) of a turbulent channel flow over porous walls. In the fluid region the flow is governed by the incompressible Navier–Stokes (NS) equations, while in the porous layers the volume-averaged Navier–Stokes (VANS) equations are used, which are obtained by volume-averaging the microscopic flow field over a small volume that is larger than the typical dimensions of the pores. In this way the porous medium has a continuum description, and can be specified without the need of a detailed knowledge of the pore microstructure by independently assigning permeability and porosity. At the interface between the porous material and the fluid region, momentum-transfer conditions are applied, in which an available coefficient related to the unknown structure of the interface can be used as an error estimate. To set up the numerical problem, the velocity–vorticity formulation of the coupled NS and VANS equations is derived and implemented in a pseudo-spectral DNS solver. Most of the simulations are carried out at $Re_{{\it\tau}}=180$ and consider low-permeability materials; a parameter study is used to describe the role played by permeability, porosity, thickness of the porous material, and the coefficient of the momentum-transfer interface conditions. Among them permeability, even when very small, is shown to play a major role in determining the response of the channel flow to the permeable wall. Turbulence statistics and instantaneous flow fields, in comparative form to the flow over a smooth impermeable wall, are used to understand the main changes introduced by the porous material. A simulation at higher Reynolds number is used to illustrate the main scaling quantities.