  We study a large class of strongly interacting condensate-like materials,
which can be characterized by a normalizable complex-valued function. A quantum
wave equation with logarithmic nonlinearity is known to describe such systems,
at least in a leading-order approximation, wherein the nonlinear coupling is
related to temperature. This equation can be mapped onto the flow equations of
an inviscid barotropic fluid with intrinsic surface tension and capillarity;
the fluid is shown to have a nontrivial phase structure controlled by its
temperature. It is demonstrated that in the case of a varying nonlinear
coupling an additional force occurs, which is parallel to a gradient of the
coupling. The model predicts that the temperature difference creates a
direction in space in which quantum liquids can flow, even against the force of
gravity. We also present arguments explaining why superfluids; be it superfluid
components of liquified cold gases, or Cooper pairs inside superconductors, can
affect closely positioned acceleration-measuring devices.
