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Numerical simulation of deformation and fragmentation of fractal-like nanoaggregates

Żywczyk Łukasz, Moskal Arkadiusz, Przekop Rafał

Chemical and Process Engineering

2019

Vol. 40, nr 4

377–-397

Aflexible fractal-like aggregate modelwas used to study deformation and fragmentation of the structure of fractal-like aggregates via their impaction with rigid rough surface.Aggregateswere conveyed one at the time towards a surface under vacuum conditions. The number of primary particles remaining in each fragment, ratio of average fragment radius of gyration after impaction to the average fragment initial radius of gyration and ratio of average coordination number to the initial coordination number were monitored for each individual aggregate. Results demonstrate that depending on the impact velocity, the fractal dimension of the aggregate, the strength of bonds between primary particles, the stiffness of the aggregate structure and the diameter of primary particle composing an aggregate, restructuring or breakage of the aggregate occur. Moreover, in the analysis of the ratio of coordination number of aggregates after impaction to the initial coordination number, three regimes were distinguished: first no deformation at low impact velocities, second restructurisation regime and finally fragmentation regime where partial or total fragmentation of aggregates was observed.

Badanie morfologii agregatów aerozolowych

Żywczyk Ł., Moskal A.

Inżynieria i Aparatura Chemiczna

2014

Nr 3

193--194

Restrykcyjne regulacje prawne określają ilość emitowanego pyłu z silników spalinowych. W większości przypadków występują jednak zagregowane cząstki tworzące nieregularne struktury, zatem oszacowanie masy może być nieprecyzyjne. Przedstawiony opis morfologiczny agregatów fraktalnych ma więc istotne znaczenie przy określaniu sumarycznej masy cząstek wytwarzanych podczas spalania paliwa np. w silnikach diesla (Diesel Exhaust Particles).

Allowed doses of emitted particles are limited by restrictive law regulations which describe quantity of soot from combustion engines. In most of cases, one deals with aggregated particles creating non-regular structures, and taking this fact into account, the estimation of mass may not be precise. Investigation of fractal aggregates morphology is a key factor in the estimation of total mass of particles produced during fuel combustion, e.g. in diesel engines.