This paper further constructs a new dark matter model based on my previous work. In this model, it is assumed that the dark matter existing in the universe exists in the form of a fluid. This dark matter fluid may be gaseous and possibly liquid. Since the scale of the universe is very large, and the dark matter fluid may encounter various disturbances when it flows, the thermodynamic parameters of dark matter in different locations, including pressure and temperature, may change. And these changes in temperature, pressure, etc., may lead to changes in the flow velocity and viscosity coefficient inside the dark matter fluid. These changes will cause changes in the Reynolds number of dark matter fluids. In fluid mechanics, we already know that if the Reynolds number exceeds a certain critical value, then the fluid will produce turbulent flow. There are many forms of turbulence, among which vortex is one of the forms of turbulence. Among the various galaxies we have observed so far, spiral galaxies are relatively common. If these spiral galaxies are turbulent flows of dark matter fluids, then we can explain many incomprehensible galactic phenomena. For example, why the scale of the Milky Way reaches 100,000 light-years, but the gravitational effect of the Milky Way can cover the entire Milky Way. In fact, using the dark matter fluid model, these problems can be easily solved if we think of each galaxy as a swirling airflow like a hurricane on Earth. In this paper, some properties of dark matter fluid are calculated, and the relationship between the viscosity coefficient and gravitational constant of dark matter fluid is analyzed. I also point out that if we can understand how the variation of the viscosity coefficient of the dark matter fluid is related to the inhomogeneity of the dark matter fluid, then we can hope to calculate the variation of the gravitational constant. So as to solve the problem of why it is difficult for us to accurately measure the gravitational constant. In addition, I have also estimated the velocity of the dark matter fluid based on some known data, and obtained approximate results of the dark matter mass, flow velocity, and viscosity coefficient. It is believed that these results will be helpful for us to further analyze the thermodynamic properties of dark matter. This paper assumes that dark matter also conforms to the laws of thermodynamics. Dark matter has volume, temperature, and pressure, and the interaction between dark matter conforms to the van der Waals equation. The dark matter fluid conforms to the conservation of momentum and energy.