Vibrational–translational energy exchange models for the direct simulation Monte Carlo method

Vijayakumar, Pradeep; Sun, Qiang; Boyd, Iain D.

doi:10.1063/1.870074

Cited by 27 publications

(24 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…See, for instance, Refs. [34][35][36][37][38][39] A simple but realistic way of accounting for the effect of inelasticity in the translational and rotational degrees of freedom is by means of a model of inelastic and rough hard spheres. In this model, collisions between spheres of components i and j are characterized by two independent constant coefficients of normal (α ij ) and tangential (β ij ) restitution.…”

Section: Introductionmentioning

confidence: 99%

Intruders in disguise: Mimicry effect in granular gases

et al. 2019

View full text Add to dashboard Cite

In general, the total kinetic energy in a multicomponent granular gas of inelastic and rough hard spheres is unequally partitioned among the different degrees of freedom. On the other hand, partial energy equipartition can be reached, in principle, under appropriate combinations of the mechanical parameters of the system. Assuming common values of the coefficients of restitution, we use kinetic-theory tools to determine the conditions under which the components of a granular mixture in the homogeneous cooling state have the same translational and rotational temperatures as those of a one-component granular gas ("mimicry" effect).Given the values of the concentrations and the size ratios, the mimicry effect requires the mass ratios to take specific values, the smaller spheres having a larger particle mass density than the bigger spheres. The theoretical predictions for the case of an impurity immersed in a host granular gas are compared against both DSMC and molecular dynamics simulations with a good agreement.

show abstract

Section: Introductionmentioning

confidence: 99%

Intruders in disguise: Mimicry effect in granular gases

et al. 2019

View full text Add to dashboard Cite

show abstract

“…This last advantage seems potentially the most promising, as high enthalpy continuum flows may involve significant internal nonequilibriumparticularly for vibrational energy but existing CFD models for inclusion of nonequilibrium internal energy distributions 22 are far more limited than those developed for DSMC. [27][28][29] While it should generally be less efficient than LD1, the LD2 approach is simpler to implement, ensures consistency with DSMC internal energy exchange procedures in a hybrid simulation, and permits extension of DSMC energy exchange models to continuum flow problems where DSMC is prohibitively expensive and other DSMC-based continuum methods give excessive numerical diffusion. Furthermore, LD2 offers the potential, as planned in future work, of incorporating DSMC chemistry models for application to continuum flows.…”

Section: Discussionmentioning

confidence: 99%

“…(6) through (9) should extend to more sophisticated DSMC models which include additional phenomena or use fewer approximations to the underlying physics. 28,29…”

Section: B Vibrational Relaxationmentioning

confidence: 99%

“…Additional capabilities developed for DSMC include consideration of collisional energy exchange within internal modes, as well as more physically based models for quantum transitions between individual vibrational energy levels. [28][29][30] Such models rely on simulated binary collisions, and likely cannot be implemented through reasonably simple modifications to the energy exchange procedures described above.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Rotational and Vibrational Nonequilibrium in a Low Diffusion Particle Method for Continuum Flow Simulation

Burt

Boyd

2009

41st AIAA Thermophysics Conference

View full text Add to dashboard Cite

A low diffusion particle method for simulating compressible low Knudsen number gas flows is modified for application to flows involving nonequilibrium distributions in rotational and vibrational energy modes. This method is closely based on the direct simulation Monte Carlo (DSMC) method, and has been developed for use in a strongly coupled hybrid scheme with DSMC. In simulations employing this hybrid scheme, the proposed modifications allow greater consistency with DSMC and reduced information loss along continuum breakdown boundaries when significant internal energy nonequilibrium effects exist within continuum flow regions. Two different approaches for rotational and vibrational nonequilibrium are proposed; the first provides greater efficiency and reduced sensitivity to time step size, while the second utilizes standard DSMC energy exchange procedures and should be easier to implement in an existing DSMC code. Both approaches are evaluated through comparison with DSMC for a set of homogeneous relaxation problems, and capabilities of the hybrid scheme are demonstrated in simulations of a hypersonic flow over a cylinder. Approved for public release; distribution unlimited.2 CFD regions, and each calculation is allowed to relax somewhat toward steady state before boundary conditions associated with the other calculation are updated. 2-5 Strongly coupled hybrid approaches involve more frequent updates to these boundary conditions, and can allow for unsteady flow simulation while avoiding potential errors due to fluctuations in quantities transported across continuum breakdown boundaries. [6][7][8][9] In recent years, a variety of hybrid CFD-DSMC schemes have been developed and applied to a range of test cases. Most of these test cases involve relatively simple flow configurations, and have been used primarily for assessment of simulation accuracy and efficiency. While CFD-DSMC hybrid schemes should also allow for accurate simulation of more complex flows for which other simulation techniques are either inaccurate or prohibitively expensive, to date these schemes have been utilized very little as engineering design and analysis tools. One reason for this may be the inherent complexity of such schemes; integration of DSMC and CFD codes tends to require extensive development timeeven if the developer has access to two pre-existing codesand coupling procedures are generally complex and difficult to implement in parallel.In an effort to develop simpler alternative DSMC-based techniques for coupled simulation of flows involving both high and low Kn regions, a number of authors have proposed modifications to DSMC for application to low Kn regimes. [10][11][12][13][14][15] The proposed DSMC-based particle methods can be categorized as either collision limiters or as direct resampling techniques. The first type of method involves a specified upper limit on the number of collisions per particle or per cell during each time step, 10,11 while in the second type of method either all or some fraction of particle velocities are...

show abstract

“…MONACO employs the Variable Soft Sphere (VSS) collision model of Koura et al [15], a variable rotational energy exchange probability model of Boyd [16] and the variable vibrational energy exchange probability model of Vijayakumar et al [17]. The flow conditions here do not involve chemical reactions.…”

Section: Description Of Experimentsmentioning

confidence: 99%