Thermal accommodation coefficients between polyatomic gas molecules and soot in laser-induced incandescence experiments

Molecular dynamics simulation of thermal accommodation coefficients for laser-induced incandescence sizing of nickel particles

“…Recently, molecular dynamics (MD) simulations have been applied to predict the thermal accommodation coefficient for TiRe-LII experiments on soot particles entrained in different gases [17][18][19]. The approach begins by defining potential energies between the atoms constituting the particle surface as well as a pairwise potential between the surface atoms and the gas molecule.…”

“…Unlike experimentally-derived values this approach does not require full morphological characterization of the aerosol particles. 1 More importantly, MD provides far more insight into the gas/surface scattering physics underlying α for LII experiments on soot, for example, how molecular mass and molecular structure influence selective energy transfer from the vibrating carbon atoms into the translational and rotational modes of the gas molecule [18].…”

The Influence of Gas–Wall and Gas–Gas Interactions on the Accommodation Coefficients for Rarefied Gases: A Molecular Dynamics Study

“…These coefficients can be fed into semi-empirical GSI models such as Maxwell's model [10] or Cercignani-Lampis-Lord (CLL) model [11] that can be employed as boundary conditions for higher-scale simulation techniques such as Direct Simulation Monte Carlo (DSMC) [12], Lattice Boltzmann method (LBM) [13], and method of moments (MoM) [14] to describe heat and mass flow at macroscopic level under rarefied condition. In literature there are various numerical studies in which MD simulations are employed to determine accommodation coefficients for different gas-solid surface combinations [15][16][17][18][19][20][21][22]. The general objective of all such investigations is to find the correlation between the energy and momentum accommodation coefficients and input parameters such as the gas temperature or purity, gas molecular weight (MW), surface condition (i.e., surface roughness, cleanness, temperature and chemistry), as well as the gas-surface interaction strength.…”

“…In most previous MD simulations [19,21,22] to compute E/MACs, the molecular beam approach was employed, in which the gas molecule adjacent to the surface is assumed to interact only with the wall atoms, and its initial velocity is sampled from an equilibrium distribution at certain temperature. Such assumptions are valid for a highly-rarefied gases (i.e., Kn > 10).…”

Pressure and Flow Residence Time Effects on Soot Properties in Counterflow Non-Premixed Hydrocarbon-Air Flames

“…The thermal accommodation coefficient represents the percentage of molecules that thermally accommodate upon collision with the laser heated soot particle, the rest undergoing specular reflection. When considering molecular geometry it is clear that the thermal accommodation coefficient is a function of the local gas composition as demonstrated using Direct Simulation Monte Carlo [97,98]. Many studies have utilized accommodation coefficient data from various molecular scattering experiments on carbon surfaces at temperatures of 700-1400 K [99,100].…”