  The impact of ion pressure dynamics on E x B mean flows is investigated.
Using a simplified, two-dimensional, drift ordered fluid model in the
thin-layer approximation, three stresses in addition to the Reynolds stress are
shown to modify the E x B mean flow. These additional terms in the stress
tensor all require ion pressure fluctuations. Quasi-linear analysis show that
these additional stresses are as important as the Reynolds stress, and hence
must be taken into account in analysis of transport barriers in which sheared E
x B mean flows are key ingredients.
