English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

For theoretical gas dynamics, the flow regimes are classified according tothe Knudsen number. For computational fluid dynamics (CFD), the numerical flowfield is the projection of the physical flow field onto the discrete space andtime, which is related to the cell Knudsen number. The real representable flowregimes are controlled by these two parameters. According to the values ofKnudsen number and cell Knudsen number, we study the classification of thenumerical flow regimes. In the process of mesh refinement, the numericalexperiments show the change of numerical flow regime from continuum, tonear-continuum, and to non-equilibrium one. The change of flow regime withdifferent cell resolution is the limitation principle for the numericalsimulation, which is the best a multiscale method can do. In other words, weshould have changeable numerical governing equations in different mesh sizescale, and they are coupled with the traditional physical equations indifferent scales, such as the Navier-Stokes and Boltzmann. Under the multiscalemodeling, a mesh refinement is a process in resolving the flow physics indifferent scale. The verification and validation (V$\&$V) need include thephysical modeling mechanism in the mesh refinement process. The traditionalidea of mesh refinement for targeting a fixed partial differential equationcannot achieve the final goal of computation, which is to recover the flowphysics as truthfully as possible under the limitation of the cell resolution.

Cell Size Effect on Computational Fluid Dynamics: The Limitation Principle for Flow Simulation