TY - JOUR
T1 - Physical Valid Scale of General Continuum Models in Unsteady Flow
AU - Yu , Yaqun
AU - Zhang , Yousheng
AU - Tian , Baolin
AU - Mo , Zeyao
JO - Communications in Computational Physics
VL - 2
SP - 503
EP - 512
PY - 2019
DA - 2019/12
SN - 27
DO - http://doi.org/10.4208/cicp.OA-2018-0103
UR - https://global-sci.org/intro/article_detail/cicp/13456.html
KW - Physical valid scale, continuum model, waves generation, contact discontinuity
thickness.
AB - <p style="text-align: justify;">A variety of numerical simulations based on continuum medium models
have been carried out in unsteady flows to explore the physical characteristics qualitatively. However, there still lack quantitative valid scales for these models, in which
scale the solutions by simulation can be treated as physically credible. In this work,
Euler and Navier-Stokes models are implemented on the typical unsteady flow with
discontinuities: Sod shock tube problem. Firstly, based on the Boltzmann model whose
valid scale is molecule kinetic scale, we compare the values of different moments of
Euler and Navier-Stokes to Boltzmann with the evolution of flow. The results provide
the valid scales of Euler and Navier-Stokes models quantitatively. Secondly, following
the real conditions and parameters in real air, the physical characteristics of waves’
generation and evolution in Sod shock tube are observed and analyzed numerically
at the microscopic level for the first time. Our results present the reference scales for
the choice of minimal simulation scale in which the continuum medium models are
used, and for the criteria whether the flow characteristics obtained by simulations can
be treated as real physical characteristics.</p>