Hongdaoshi walked more than ten kilometers northwest and saw a cloud of black gas falling into the mountain. He tracked it down and saw a bare rock, very incongruous with the lush woods around him. Master Hong scraped the stones with an ancient knife and found sparks on the stones. The harder he scrapes, the bigger the spark. It is not surprising that Master Hong thought that there was a stone called flint, which was meant to spark. The Hongdao Master scraped the stone vigorously, and the spark grew bigger and bigger, and turned into an open flame.

In the light of the fire, some strange characters faintly appeared, which Hong Daoist did not recognize, and he judged that this was a special text for divination. After the fire burned, a skeleton appeared in front of the Hongdao Master, and a suffocating and terrifying voice floated out of the skeleton's mouth: "Whoever disturbs my peace will die!" "Before he could escape, he was shut in by a stone door.

It was pitch black in the stone cave, and Hong Daoist couldn't see anything. He went to push the stone gate just now, but the stone gate was gone. Master Hong saw a cave in front of him, and there was a faint light at the entrance of the cave, which seemed to be the exit. Hong Daoshi dragged his tired legs to walk in the cave, feeling that something was missing in his hand, and when he looked closely, it turned out that the treasure knife was missing, and it may have fallen somewhere. He looked back, but couldn't find it, so he had to go back and walk towards the exit.

Suddenly, several stones flew in from the light at the entrance of the cave, and before he could dodge, he fell to the ground, and the stones fell behind him, filling the cave. Stones flew in from the hole, clogging up the space behind the Floodmaster. Sensing that the stones were about to bury him, he did not dare to stand up, so he had to crawl forward in the cave. There were more and more stones, piled up faster and faster, and the Hongdao Master couldn't win, and these stones pressed directly on his back.

Hong Daoist knew that he had encountered a dense rock formation, and this formation was much more powerful than the Eight Formations. During the Three Kingdoms era, Liu Bei attacked Wu, and after the fiasco of the Battle of Yiling, Zhuge Liang used the Eight Formations to stop Lu Xun's pursuers. These eight formations are nothing more than using some stones to arrange and combine them in a certain way. The eight-array diagram is not filled with rocks, there is a lot of space inside. However, the dense stone formation in front of him has been completely filled with stones.

Hung Daoshi thought he was going to die in the cave, and to his strange feeling, the stones pressed down on him, and he didn't feel the slightest pain. He even saw that the stone had passed through his body, and his physical body seemed to be non-existent. Hong Daoshi bit his finger, but he didn't bite anything, and he didn't feel any pain, he finally realized that he didn't exist in real form, it turned out that his soul was trapped by the skull, and his body and treasure knife were outside the mountain rock.

It turned out that this was the conspiracy of the Yin Devouring King, who turned into a cloud of black qi and lured Hong Daoshi into this dense mountain rock, trying to trap him to death. The stone has sealed all the caves, and the soul or stream of consciousness of the Hongdao Master cannot walk normally like a human, and can only keep squirming between the cracks of the stones. When he tried to sit up, he found that his body was deformed and could flow through the pores, but the resistance was too great, and the flow speed was very slow, and it took a long time to flow from the cracks in the stones to the exit.

Fine grains of sand continue to fill in the gaps of the stones, and the pore radius becomes smaller and smaller, almost reaching the scale of micrometers and nanometers. Hong Daoist urged the true qi in his body, and a warm air flow ran in his second vein. With a "bang", the air flow exploded, and the body of the Hongdao Master's soul state turned into a stream of gas with a stream of consciousness. The consciousness stream gas of Hongdaoshi flows in multi-scale pore spaces and cracks at the millimeter, micro, and nanoscale, and its flow regimes include viscous flow, slip flow, transition flow, Knudsen diffusion, and surface diffusion.

Physics tells us that the average distance traveled between two collisions of a gas molecule is called the mean free path. When the pore radius is much larger than the mean free path of the stream of consciousness gas molecules of the Hongdaoist, the viscous flow generated by the collision between the gas molecules dominates, and the collision between the molecules and the pore wall surface is negligible. The stream of consciousness gas molecules of the Hongdao Master are viscous in this flow range, which can be expressed by Darcy's law, and he moves most easily in this flow regime.

With the decrease of the spatial scale of the flow, the flow of the gas molecules of the stream of consciousness of the Hongdaoist is manifested as a slip flow, and in this flow range, on the one hand, the gas can still be considered as a continuous flow medium, satisfying the Darcy flow equation. On the other hand, the velocity of the gas flow along the pore wall is non-zero, there is a slippage effect, and the gas flow satisfies the Klinkenberg equation. Consciousness flow gases can be corrected for viscous flow by slip flow within this flow range.

What does it mean that the velocity of a pore wall is not zero? We know that the closer the river is to the banks, the slower it becomes, and on the walls of the banks, the velocity of the water is zero. The same goes for the movement of the gas in the capillary, if there is no slip, the velocity of the molecules on the wall is zero, and if there is a slip flow, the velocity of the gas molecules on the wall is not zero.

When the mean free path of the stream of consciousness gas molecules is in the same order of magnitude relative to the pore radius of the flow, the collision between the gas molecules and the pore wall is the main influencing factor, and the gas molecules will diffuse freely as a single molecule instead of in the form of a macroscopic group of molecules, and Knudsen diffusion occurs for the stream of consciousness gas molecules. Between the Knudsen diffusion and slip flow, there is also a transition flow.

During the movement of the stream of consciousness gas molecules of Hongdaoshi, due to the effect of the concentration gradient, the molecules adsorbed on the surface of the pore medium will move along the solid surface and cause surface diffusion, which is also an important transport mechanism of gases. Scientists have conducted very detailed and in-depth studies on the mechanism of multiple migration of gases in porous media. These scientists do not seek fame, do not make profits, conduct research in obscurity, and contribute to humanity in obscurity, which is incomprehensible to those stars or little fresh meat who are keen on spotlights and walking the red carpet.

When the Yin Devourer King besieged the Flood Master's stream of consciousness gas molecules, he only considered the viscous flow of molecules, but he didn't expect that the Flood Master's stream of consciousness gas molecules also had other forms such as slip flow, transition flow, Knudsen diffusion, and surface diffusion, and his actual flow speed was far greater than the flow speed calculated by the Yin Devouring King.

The dense rock formation of the Yin Devouring King finally did not trap the Hongdao Master, and before the Hongdao Master starved his physical body, his stream of consciousness ran out of the dense rock, becoming one with the physical body, and his body moved freely. Because the Yin Devourer King only knew evil arts, did not understand science, and did not understand the seepage mechanism of gases in dense rocks, his conspiracy to besiege the Flood Master went bankrupt.

It took a total of twenty-four hours for the soul or stream of consciousness of the Hongdao Master to escape. He felt very hungry, so he searched for melons and fruits in the mountains, ate the dry food he brought, and regained his strength. Angry at this Yin Devouring King, Daoist Hong slashed the rock where he was imprisoned several times with his ancient knife, and red liquid oozed from the stone, like a blood stain.

Coming down from the mountain, it was getting late, the village was already curling with smoke, and some of the occupants had turned on the electric lights, which shone in the light of the twilight, pointing the way to the night walkers in the dark.