周期変動流中の微粒子運動解析におけるバセット項の影響

Abstract

The motion of small particle in sinusoidal oscillating air flows is investigated numerically by Tchen equation with Crank-Nicholson method. The velocities of water particles whose diameter are 1, 10 and 100 micrometer are calculated in oscillating air flows in the frequency range from 1 Hz to 1 MHz. The result of analysis indicates that the amplitudes of particle velocity which are deduced including Basset term differ from those without Basset term, and the maximum error in the amplitude of particle velocity is four percent of the amplitude of fluid velocity at non-dimensional frequency f(sub tau(sub p)) of 0.3. This error is reduced as the non-dimensional frequency f(sub tau(sub p)) increased as well as decreased from 0.3, and the frequency range which the error is less than two percent is f(sub tau(sub p)) less than or equal to 0.08 or f(sub tau(sub p)) greater than or equal to 2.0.

正弦的脈動空気流中の微粒子の運動をクランク-ニコルソン法とチエン方程式を用いて数値解析した。脈動空気流中の水粒子(直径1,10,100μm)の速度を1Hz?1MHzの周波数範囲で計算した。解析結果によると、バセット項を考慮した場合の粒子速度の振幅はバセット項を省略した場合の振幅とは違っており、その最大誤差は無次元化周波数f(τ(p))=0.3で流体速度の振幅の4%になる。この誤差は無次元化周波数が0.3より増加したり減少したりするにつれて減少する。この誤差が2%以下になる周波数範囲はf(τ(p))≦0.08またはf(τ(p))≧2.0である。