CAJ | 학술논문

协调系数是反映气体与壁面动量和能量交换的重要参数,可通过分子动力学方法进行统计,其二维模拟由于计算量较三维大大减小而逐渐得到应用.法向动量协调系数表达式中的p_(nw)和能量协调系数表达式中的E_w分别表示气体分子在壁面漫反射后的平均法向动量和平均能量,利用气体动理论推导发现,二维的p_(nw)与三维相同,而E_w则由于降维小于三维的结果,导致能量协调系数的表达式在二维计算中有别于三维.依据协调系数的表达式,使用分子动力学方法模拟三维和二维系统中的导热问题,结果表明,二维能量协调系数与三维相比较小,而法向动量协调系数差别不大.
협조계수시반영기체여벽면동량화능량교환적중요삼수,가통과분자동역학방법진행통계,기이유모의유우계산량교삼유대대감소이축점득도응용.법향동량협조계수표체식중적p_(nw)화능량협조계수표체식중적E_w분별표시기체분자재벽면만반사후적평균법향동량화평균능량,이용기체동이론추도발현,이유적p_(nw)여삼유상동,이E_w칙유우강유소우삼유적결과,도치능량협조계수적표체식재이유계산중유별우삼유.의거협조계수적표체식,사용분자동역학방법모의삼유화이유계통중적도열문제,결과표명,이유능량협조계수여삼유상비교소,이법향동량협조계수차별불대.
Accommodation coefficients,important parameters in momentum and energy exchange between a gas and wall,are mainly calculated with molecular dynamic(MD) method.Since the computational cost in a two-dimensional(2D) system is highly reduced from the three-dimensional (3D) one,the 2D MD method has been applied in recent researches.p_(nw) in the definition of normal momentum accommodation coefficients(NMAC) and E_w in the definition of energy accommodation coefficients(EAC) are average normal momentum and energy for those diffusively reflected gas molecules,respectively.Expressions of P_(nw) and E_w were deduced from the kinetic theory that,in the 2D system with lower dimension,p_(nw) was equal while E_w was smaller,resulting the different EAC expression.Furthermore,the NMAC and the EAC were calculated in thermal conductions using 2D and 3D MD with corresponding expressions.The results revealed that the 2D EAC were smaller than the 3D ones.while the NMAC was maintained.