Table 1 Expressions of the coefficients in Eqs (57) in the main text.

From: Electrification in granular gases leads to constrained fractal growth

Coefficient

Expression

\( {\mathcal B} \)

\({k}_{e}\langle \delta {q}^{2}\rangle /(Td)\)

\(l\)

\(\sqrt{4-{ {\mathcal B} }^{2}}\)

\({l}_{1}\)

\(\sqrt{1-{ {\mathcal B} }^{2}}\)

\({C}_{res}^{T}\)

\(80\,{2}^{1/5}\,{d}^{2}{C}_{\epsilon }m/(21\sqrt{\pi }{m}^{8/5})\)

\({C}_{agg}^{T}\)

\({d}^{2}\mathrm{/(8}\sqrt{\pi m})\)

\({C}_{res}^{q}\)

\(1.4080\,{d}^{2}{C}_{{\rm{\Delta }}q}^{2}\mathrm{(2}+\eta \mathrm{)(4/}m{)}^{\eta +\mathrm{1/2}}/\pi \)

\({C}_{agg}^{q}\)

\(4{d}^{2}/\sqrt{\pi m}\)

\({C}_{agg}^{n}\)

\({d}^{2}\mathrm{/(2}\sqrt{\pi m})\)

\({a}_{1}^{T}\)

\( {\mathcal B} \mathrm{(8}-5{ {\mathcal B} }^{2})l+\pi \mathrm{(16}-10{ {\mathcal B} }^{2}+3{ {\mathcal B} }^{4})\)

\({a}_{2}^{T}\)

\(-\,32+20{ {\mathcal B} }^{2}-6{ {\mathcal B} }^{4}\)

\({a}_{3}^{T}\)

\(l\mathrm{(2}\pi {({ {\mathcal B} }^{2}-\mathrm{4)}}^{2}+ {\mathcal B} (\,-\,32+28{ {\mathcal B} }^{2}+{ {\mathcal B} }^{4}))\)

\({a}_{4}^{T}\)

\(-\,\mathrm{4(32}-20{ {\mathcal B} }^{2}+9{ {\mathcal B} }^{4})\)

\({a}_{5}^{T}\)

\(l {\mathcal B} (\,-\,32+28{ {\mathcal B} }^{2}+{ {\mathcal B} }^{4})\)

 

\(+\,2\pi ({ {\mathcal B} }^{2}\mathrm{(20}-8l)+{ {\mathcal B} }^{4}(\,-\,9+l)+\mathrm{16(}\,-\,2+l))\)

\({a}_{6}^{T}\)

\(\mathrm{4(32}-20{ {\mathcal B} }^{2}+9{ {\mathcal B} }^{4})\)

\({a}_{1}^{q}\)

\(2 {\mathcal B} l({ {\mathcal B} }^{2}-\mathrm{1)}-\pi \mathrm{(4}-2{ {\mathcal B} }^{2}+{ {\mathcal B} }^{4})\)

\({a}_{2}^{q}\)

\(\mathrm{2(4}-2{ {\mathcal B} }^{2}+{ {\mathcal B} }^{4})\)

\({a}_{3}^{q}\)

\(16l\sqrt{\pi }{l}_{1}{\mathrm{(4}-5{ {\mathcal B} }^{2}+{ {\mathcal B} }^{4})}^{2}\)

\({a}_{4}^{q}\)

\(-\,\sqrt{\pi } {\mathcal B} l(\pi ({ {\mathcal B} }^{2}-\mathrm{4)(1}+2{ {\mathcal B} }^{2})\)

 

\(+\,2 {\mathcal B} {l}_{1}(\,-\,8-54{ {\mathcal B} }^{2}+33{ {\mathcal B} }^{4}+2{ {\mathcal B} }^{6}))\)

\({a}_{5}^{q}\)

\(2\sqrt{\pi } {\mathcal B} {l}^{5}\mathrm{(1}+2{ {\mathcal B} }^{2})\)

\({a}_{6}^{q}\)

\(16\sqrt{\pi } {\mathcal B} {l}_{1}^{5}\mathrm{(4}+5{ {\mathcal B} }^{2})\)

\({a}_{7}^{q}\)

\(8l\sqrt{\pi }{l}_{1}{\mathrm{(4}-5{ {\mathcal B} }^{2}+{ {\mathcal B} }^{4})}^{2}\)

\({a}_{8}^{q}\)

\(-\,\sqrt{\pi } {\mathcal B} {l}^{5}\mathrm{(1}+2{ {\mathcal B} }^{2})\)

\({a}_{9}^{q}\)

\(\sqrt{\pi } {\mathcal B} {l}_{1} {\mathcal B} l\mathrm{(8}+54{ {\mathcal B} }^{2}-33{ {\mathcal B} }^{4}-2{ {\mathcal B} }^{6})\)

\({a}_{10}^{q}\)

\(8\sqrt{\pi } {\mathcal B} {l}_{1}{({ {\mathcal B} }^{2}-\mathrm{1)}}^{2}\mathrm{(4}+5{ {\mathcal B} }^{2})\)

\({a}_{1}^{n}\)

\(-\,{ {\mathcal B} }^{2}{l}^{3}\)

\({a}_{2}^{n}\)

\({l}_{1}l {\mathcal B} (\,-\,4+7{ {\mathcal B} }^{2})+{l}_{1}\pi ({ {\mathcal B} }^{2}-1)(8-4l+{ {\mathcal B} }^{2}(\,-\,6+l))\)

\({a}_{3}^{n}\)

\(4{l}_{1}\mathrm{(4}-7{ {\mathcal B} }^{2}+3{ {\mathcal B} }^{4})\)

\({a}_{4}^{n}\)

\(-\,{ {\mathcal B} }^{2}{l}^{3}\)

\({a}_{5}^{n}\)

\({l}_{1}l( {\mathcal B} (\,-\,4+7{ {\mathcal B} }^{2})+\pi \mathrm{(4}-5{ {\mathcal B} }^{2}+{ {\mathcal B} }^{4}))\)

\({a}_{6}^{n}\)

\(-\,4{l}_{1}(4-7{ {\mathcal B} }^{2}+3{ {\mathcal B} }^{4})\)

  1. Here \(m\) and \(d\) are the mass and size of the aggregates. The material constant \({C}_{\epsilon }\) [Eq. (31)] influences the viscoelastic properties of the particles, while \({C}_{{\rm{\Delta }}q}\) and \(\eta \) [Eq. (28)] influence the charge buildup. Other notations are as described in the main text.