Low-cost viscometer based on energy dissipation in viscous liquids

We describe a new type of low-cost easy-to-use viscometer based on the temp erature elevation in a liquid under shear flow. After calibration, this ins trument can be used to measure the apparent steady state viscosity for both Newtonian and non-Newtonian liquids with no yield stress. We compute the r ise in temperature due to viscous dissipation in a Couette cell and compare it to experimental results for different fluids. We show that the variatio n of the temperature with shear rate can be used to characterize the theolo gical behaviour of viscous fluids and to evaluate their viscosity in a. lar ge domain, from typically a few cP np to more than 10 P, with an accuracy o f about +/- 5%. In contrast to simple viscometers, non-Newtonian fluids can be studied with this apparatus. We give experimental results for Newtonian and non-Newtonian liquids and show that they are very similar to those giv en in the literature by using much more sophisticated instruments.