  We have researched the motion of gas in the subnanochannel with functional
surface which wettability has a gradient for the fluid by using molecular
dynamics simulation. The results show that the gas is driven to flow under a
single heat source and without any other work or energy applied to the system.
The driving source is owed to the potential gradient of the functional face
which keeps the fluid running in the subnanochannel. The width of the channel
and the pressure of the reservoir has a significant influence on the flow
velocity, which, respectively, has an optimal value for the maximum velocity.
The flow velocity grows with the increasing temperature.
