Award Date


Degree Type


Degree Name

Master of Science (MS)


Physics and Astronomy

First Committee Member

Zhaohuan Zhu

Second Committee Member

Chao-Chin Yang

Third Committee Member

Jason Steffen

Fourth Committee Member

Rebecca Martin

Fifth Committee Member

Pengtao Sun

Number of Pages



The radial pressure gradient (RPG), along the midplane of gaseous protoplanetary disks (PPD) – planetary nurseries – poses a severe obstacle to planet formation. Micron-sized dust grains, embedded in the disc, must quickly grow to kilometer-sized planetesimals – the building blocks of planets – before fatally drifting inwards, by RPG-induced gas drag, into a central host star. However, the RPG simultaneously powers one of the most robust processes to overcome this radial-drift barrier: the streaming instability (SI). Spontaneously triggered, the SI aerodynamically concentrates drifting dust via drag-induced, coupled interactions and feedback with the surrounding gas. In particular, the non-linear phase of the SI has not been rigorously or thoroughly studied in the presence of different RPGs, despite implications and expectations from linear analysis. Thus, we numerically simulate and analyse the non-linear evolution of the SI among various RPGs in unstratified, 2D shearing sheets, corotating with the disc, using the Athena++ code, extended to include Lagrangian particles with feedback to the gas. Depending on particle size and initial dust concentration, we find that different RPGs noticeably affect the non-linear growth, saturation, structure, and resultant dust density distributions of the SI, the details of which are not obvious nor expected from linear analysis. Our results offer many new, valuable insights into the complexity of dust-gas dynamics as well as implications for both planet formation theories and PPD observations.


asteroids comets Kuiper belt objects; computational fluid dynamics; hydrodynamics; instabilities; simulations; turbulence


Astrophysics and Astronomy | Other Physics | Physics

File Format


File Size

2200 KB

Degree Grantor

University of Nevada, Las Vegas




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