Zero-Dispersion Limit for the Benjamin–Ono Equation on the Torus with Bell Shaped Initial Data

We consider the zero-dispersion limit for the Benjamin–Ono equation on the torus. We prove that when the initial data is bell shaped, the zero-dispersion limit exists in the weak sense and is uniform on every compact time interval. Moreover, the limit is equal to the signed sum of branches for the multivalued solution of the inviscid Burgers equation obtained by the method of characteristics. This result is similar to the one obtained by Miller and Xu for the Benjamin–Ono equation on the real line for decaying and positive initial data. We also establish some precise asymptotics of the spectral data with initial data $$u_0(x)=-\beta \cos (x)$$ , $$\beta >0$$ , justifying our approximation method, which is analogous to the work of Miller and Wetzel concerning a family of rational potentials for the Benjamin–Ono equation on the real line.