The structure of the narrow groove is very simple, mainly composed of two parallel plates. For the slow flow of viscous fluid (water or glycerin, etc.), there is a certain gap between parallel plates (the gap width is about 0.8-3.5 mm). ). The flow region can be used as a prototype model. The boundary conditions of the model are the same as those in the seepage area: common impervious gaskets are used to simulate the water-resisting boundary; The permeability boundary is simulated by connecting with water supply or drainage system to adjust water level or flow.

Narrow slots are usually assembled vertically and horizontally. Whether vertical or horizontal, at least one of the two parallel plates should be made of transparent plexiglass plate, so as to observe and record the seepage elements, as shown in Figure 8-2.

Figure 8-2 Schematic Diagram of Narrow Slot Structure

Vertical slit can be used to simulate the two-dimensional flow problem of vertical slit flow in cross section. When simulating free surface flow, the boundary conditions of free surface and seepage surface can be automatically generated except the boundary conditions of bottom and side. If a water distribution pipe is installed at the top and a set of drainage holes are set at the bottom, the infiltration term and evaporation term of free surface flow can be simulated.

Horizontal narrow slot can be used to simulate two-dimensional flow problems on the plane. When simulating confined flow, discrete water storage pipes are often set on the upper plate to simulate the elastic water storage rate of aquifer. If the cross-sectional area of the water storage pipe itself is a, the control area of the pipe is f and the gap width is b, then the water storage rate of the model is micron =A/Fb. If a hole is drilled in the lower plate, a switch is installed and connected to the water supply or drainage system, a water injection well or a production well can be simulated. When simulating the restricted flow of overflow recharge, we can insert equal thickness plug plates with grids between parallel plates to simulate the weak permeable layer, and simulate the overflow through the grid water flow.

No matter vertical or horizontal grooves, usually only homogeneous isotropic media can be simulated. If it is necessary to simulate heterogeneity and anisotropy, it is necessary to modify the narrow slit appropriately.