In this paper, we study the fluid-dynamical limit of the Boltzmann equation for a polyatomic gas with a soft potential collision kernel function based on the extended Grad assumption, which involves the continuous internal energy I and the molecular degrees of freedom α. Using the L2 ∩ L∞ framework, we prove the local existence of Lv,I2∩Lv,I∞ weak solutions to this moldel and obtain the compressible Euler limit from this Boltzmann equation by using the Lv,I2∩Lv,I∞ energy estimate with establing some new properties of the collison operator.
Wang et al. (Sun,) studied this question.