Lubricant rheology governs the friction in any lubricated contact. In hydrodynamic lubrication, the genesis of friction is well-understood. However, when asperity contacts occur, the situation becomes more complex. In this “mixed” lubrication regime, it is known that lubricants can deviate dramatically from Newtonian behavior, but the source of this effect has not been identified. In particular, the question arises as to whether the non-Newtonian behavior of the lubricant is due to the extreme thinness of the film or to the very large shear rates to which it is subjected. In the current work, we analyze friction force measurements in the magnetic slider/disk interface to help resolve this question. Because of its precision geometry, the slider/disk interface is ideal for such an investigation. Results of the analysis indicate (1) the lubricant retains its bulk viscosity in films as thin as 11–12 molecular diameters; (2) the rheological state of the lubricant is determined by a parameter we introduce here as the “Newtonian” shear stress, and (3) the rheology of the lubricant at high Newtonian shear stress may indicate a newly discovered property of liquids.

Visualization of airflow in an office room with all its heating sources turned on is presented in this paper. The simulations were conducted using SolidWorks flow simulation and the room selected for this study was Savannah State University's (SSU's) Hubert D-414. In a previous analysis, a similar study was conducted without any heat source; this is a continuation of that work. The furniture and the office equipment were created as SolidWorks Part files and then assembled with room's floor, roof, and sidewalls to create an exact replica of the room. One of the pre-defined fans from the software was selected to simulate the airflow. The flow visualization videos show a very clear view of how the airflow from the fan distributes the heat inside the room. The fan created two streams of airflow. The one on the top does not significantly affect the temperature of the room. It just creates an air circulation close to the roof. The heat from the heating sources is actually picked up with the lower air currents and distributed around the room. The flow visualization also shows that the air gets warm while it moves toward the exit.