Jeffery-Hamel flow: an experimantal study of instabilities, bifurcations and multiple solutions*

We present an experimental realization of the classical Jeffery-Hamel flows inside a wedge-shaped channel. We measure the velocity fields in the nearly-two-dimensional flow produced in our experimental apparatus, and compare the data with the predictions of Jeffery-Hamel theory. The flow is governed by two dimensionless parameters, the Reynolds number $R$ and the wedge angle $\alpha$. In the plane of these parameters, we perform a detailed study of bifurcation diagrams for the solutions that reveals the absolute stability of the pure outflow solution and an interesting hysteretic structure for bifurcations. We also observe a multiple-vortex flow regime predicted earlier numerically and analytically.