Abstract: It is often desirable to meter multiphase fluid flow in pipes (e.g. bore holes). In order to obtain reliable/accurate flow rate measurements it is known to incorporate obstructions in the flow path to cause homogenization. A non-obstructive method of homogenizing the flow of a multiphase mixture of fluids in a bore hole comprises providing in the bore hole a pipe section which has an internal surface with a step discontinuity, whereby when fluid flows through the pipe section, turbulent stresses are caused by the discontinuity, leading to homogenization by turbulent mixing. There is disclosed a flow meter which comprises a pipe length with a first section having a step change in cross-section for homogenizing fluid flow therethrough, in series with a venturi flow meter in which a differential pressure can be measured in a second pipe section having a smooth change in cross-section.