2.1 Boltzmann Transport Equation

"확산계수, 열전도 계수, 점성과 같은 재료의 거시적 특성은 어떻게 원자 단위의 미시적 세계에서 결정이 되는가?"

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[1] Boltzmann Transport Equation
(1) distribution function, f(r, c, t) : 시각 t에서 위치 범위 = (r, r+dr), 속도 범위 = (c, c+dc)를 갖는 입자들의 분율
(2) 만약 단위질량을 가지는 기체 입자에 외력 F가 작용한다면 속도는 c에서 c+Fdt, 위치는 r에서 r+cdt로 변화할 것.
(3) 입자들간의 충돌이 발생하지 않는다면, 외력 작용 전후로의 distribution function의 차이는 없을 것.
(4) 하지만 입자들간의 충돌이 발생한다면, interval drdc에 대한 distribution function에 차이가 발생할 것.
(4-1) 이러한 차이를 collision operator라 부름(아래 수식화 참고).