Previous MHD simulations have shown that wind ( i.e. , uncollimated outflow ) must exist in black hole hot accretion flows .
In this paper , we continue our study by investigating the detailed properties of wind , such as mass flux and poloidal speed , and the mechanism of wind production .
For this aim , we make use of a three dimensional GRMHD simulation of hot accretion flows around a Schwarzschild black hole .
The simulation is designed so that the magnetic flux is not accumulated significantly around the black hole .
To distinguish real wind from turbulent outflows , we track the trajectories of the virtual Largrangian particles from simulation data .
We find two types of real outflows , i.e. , a quasi-relativistic jet close to the axis and a sub-relativistic wind subtending a much larger solid angle .
We confirm that the mass flux of wind is very significant and most of the wind originates from the surface layer of the accretion flow .
The radial profile of the wind mass flux can be described by \dot { M } _ { wind } \approx \dot { M } _ { BH } ( r / 20 r _ { s } ) , with \dot { M } _ { BH } being the mass accretion rate at the black hole horizon and r _ { s } being the Schwarzschild radius .
The poloidal wind speed almost remains constant once they are produced , but the flux-weighted wind speed roughly follows v _ { p,wind } ( r ) \approx 0.25 v _ { k } ( r ) , with v _ { k } ( r ) being the Keplerian speed at radius r .
The mass flux of jet is much lower but the speed is much higher , v _ { p,jet } \sim ( 0.3 - 0.4 ) c .
Consequently , both the energy and momentum fluxes of the wind are much larger than those of the jet .
We find that the wind is produced and accelerated primarily by the combination of centrifugal force and magnetic pressure gradient , while the jet is mainly accelerated by magnetic pressure gradient .
Finally , we find that the wind production efficiency \epsilon _ { wind } \equiv \dot { E } _ { wind } / \dot { M } _ { BH } c ^ { 2 } \sim 1 / 1000 , in good agreement with the value required from large-scale galaxy simulations with AGN feedback .