What is aperture? What is porosity?

Holes are the same as particles, and because of the connectivity of the pores, the situation is more complicated. Closed holes are difficult to measure. There are two types of openings: one is a through hole, which has exits at both or multiple ends; the other is a blind hole (or semi-through hole), which has an exit at only one end. Most of the channels are winding and connected by a series of holes of various hole shapes. Therefore, the complexity of various hole shape problems lies in the fact that in addition to the shape factor, a bending factor also needs to be introduced. Hole shapes include inkwell-shaped, cylindrical, conical, triangular and other irregular shapes. Therefore, different measurement methods of holes must set the hole model to facilitate calculation. At present, most hole models are set to be cylindrical, and some are also calculated using the concept of hydraulic radius. The so-called hydraulic radius is defined as the cross-sectional area of the hole divided by its circumference.

The concept of pore size varies with different testing methods and pore size calculation methods, but they are all characterized by the radius of the pore. This and the particle size represent the difference in particle size. You need to remember it at all times, otherwise the particle size or pore size values will be different. Double.

Porosity refers to the volume occupied by the pores in a particle accumulation body or a porous body, and is calculated by dividing the total pore volume by the pile volume or the surface volume of the porous body.