Transient growth of small disturbances in a Jeffrey fluid flowing through a pipe

Abstract

The hydrodynamic stability of small disturbances in a non-Newtonian fluid flowing through a circular pipe is studied analytically. Specifically, the time development of the disturbances and the transient disturbance amplification are studied. The non-Newtonian fluid is modelled by a two-constant Jeffrey model characterized by the relaxation time ( λ) and a constant ( K) representing the ratio of relaxation to retardation times. All the investigations are carried out for streamwise-independent disturbances since they are the most amplified ones in a Newtonian fluid and can be treated analytically. The eigenvalue problem and the initial value problem for the disturbances are studied. Compared to the Newtonian case, the results show that dependent on K and λ, a reduction or an increase of the disturbance transient growth may occur.