Aerodynamic properties of fractal grains: Implications for the primordial solar nebula
Aerodynamic properties of fractal grains: Implications for the primordial solar nebula
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分形颗粒的空气动力学特性：对原始太阳星云的影响
DOI：
10.1086/185172
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
B. Donn
中科院分区：
文献类型：
--
作者：
P. Meakin;B. Donn
在原始太阳星云和致密星际云的条件下，小颗粒具有较低的相对速度。这是有效粘附和形成分形聚集体的条件。计算分形簇的横截面σ与初级粒子数N的比值得出1 n σ/N = 0.2635 + 0.5189Nsup（-0.1748）。该比值随N缓慢减小，当N较大时接近常数。在通常的假设下，碰撞产生球形紧凑，均匀密度的聚集体，σ/N变化为Nsup-1/3，并迅速下降。因此，分形颗粒比致密聚集体更紧密地耦合到气体。这对聚集体的空气动力学行为有着重要的影响，因此也对聚集体和星云的演化有着重要的影响。
Under conditions in the primordial solar nebula and dense interstellar clouds, small grains have low relative velocities. This is the condition for efficient sticking and formation of fractal aggregates. A calculation of the ratio of cross section, sigma, to number of primary particles, N, for fractal clusters yielded 1n sigma/N = 0.2635 + 0.5189N sup (-0.1748). This ratio decreases slowly with N and approaches a constant for large N. Under the usual assumption of collisions producing spherical compact, uniform density aggregates, sigma/N varies as N sup -1/3 and decreases rapidly. Fractal grains are therefore much more closely coupled to the gas than are compact aggregates. This has a significant effect on the aerodynamic behavior of aggregates and consequently on their evolution and that of the nebula.