# Oscillatory travelling wave solutions for coagulation equations

## TL;DR

This paper constructs oscillatory traveling wave solutions for a class of coagulation equations with kernels of homogeneity one, revealing their shape and oscillatory nature through asymptotic analysis.

## Contribution

It introduces a formal method to construct and analyze oscillatory traveling wave solutions for coagulation equations with specific kernels.

## Key findings

- Traveling waves are oscillatory with increasing oscillation strength as epsilon decreases.
- Asymptotic expansions describe the detailed shape of these oscillatory solutions.
- Supports the conjecture that solutions converge to oscillatory traveling waves for large times.

## Abstract

We consider Smoluchowski's coagulation equation with kernels of homogeneity one of the form $K_{\varepsilon }(\xi,\eta) =\big( \xi^{1-\varepsilon }+\eta^{1-\varepsilon }\big)\big ( \xi\eta\big) ^{\frac{\varepsilon }{2}}$. Heuristically, in suitable exponential variables, one can argue that in this case the long-time behaviour of solutions is similar to the inviscid Burgers equation and that for Riemann data solutions converge to a traveling wave for large times. Numerical simulations in \cite{HNV16} indeed support this conjecture, but also reveal that the traveling waves are oscillatory and the oscillations become stronger with smaller $\varepsilon$. The goal of this paper is to construct such oscillatory traveling wave solutions and provide details of their shape via formal matched asymptotic expansions.