“…In this paper, among the available Herschel and Bulkley formulations, i.e. three-equation (Balmforth and Liu, 2004;Di Cristo et al, 2013d;Huang and Garcia, 1998) or two-equation (Ancey, 2001(Ancey, , 2005Ancey et al, 2012;Coussot, 1997;Laigle and Coussot, 1997) models, the latter, which is more usually adopted in engineering applications, is considered.…”