Pascal's law

Abstract: We set up the problem of finding the transition state for phase nucleation in multi-component fluid mixtures, within the Landau-Ginzburg density functional. We establish an expression for the coordinate-dependent local pressure that applies to mixtures, arbitrary geometries, and certain non-equilibrium configurations. The expression allows one to explicitly evaluate the pressure in spherical geometry, a la van der Waals. Pascal’s law is recovered within the Landau-Ginzburg density functional theory, formally analogously to how conservation of energy is recovered in the Lagrangian formulation of mechanics. We establish proper boundary conditions for certain singular functional forms of the bulk free energy density that allow one to obtain droplet solutions with thick walls in essentially closed form. The hydrodynamic modes responsible for mixing near the interface are explicitly identified in the treatment; the composition at the interface is found to depend only weakly on the droplet size. Next we develop a Landau-Ginzburg treatment of the effects of amphiphiles on the surface tension; the amphiphilic action is seen as a violation of Pascal’s law. We explicitly obtain the binding potential for the detergent at the interface and the dependence of the down-renormalization of the surface tension on the activity of the detergent. Finally, we argue that the renormalization of the activation barrier for escape from long-lived structures in glassy liquids can be viewed as an action of uniformly seeded, randomly oriented amphiphilic molecules on the interface separating two dissimilar aperiodic structures. This renormalization is also considered as a “wetting” of the interface. The resulting conclusions are consistent with the random first order transition theory.

Abstract: Beboo is a bilingual (English-Indonesia) interactive e-Book with virtual laboratory feature. Beboo has been developed in Static Fluids Concept for teaching package. It contains many contents like pressure, hydrostatic pressure, Pascal law, Archimedes law, capillarity, viscosity and surface tension. In experiment process, this e-Book supports the virtual laboratory, U-Pipe system. Beboo is designed to succeed the international program in senior high school level in Indonesia as the learning source. Twenty-four students have been used Beboo in the classroom. This particular research explored the student responds to this e-Book. Students have been tried the U-pipe virtual laboratory and determined the density of the fluid from that activity. As the result, students found Beboo to be a positive learning experience with all the content, language, media and learning aspects state in a good and very good category. It means the student can use and simulate the experiment to determine the density of the fluid. However, students have a problem in language aspect. The data showed this aspect state in lowest respond percentage (73%) than others.

Abstract: Flow-reaction forces acting in hydraulic valves have been studied for many decades. Despite this, they are difficult to account for due to the complexities of the jet flow. This paper focuses only on the reduction, also referred to as compensation, of the flow force as applied to a valve spool featuring a profile of a turbine bucket. Fluid power textbooks explain the compensation taking place on such a profile by applying Newton laws of motion to the profile and deliver an equation for the magnitude and the direction of the flow force. This paper shows that both the magnitude and the direction of the compensating flow force are incorrect if calculated from the textbook equation. A corrected analysis of the dynamic forces is presented that are in agreement with earlier experiments by this author. It follows that the compensating flow force should be calculated from the static-pressure imbalance on the spool profile. That is, not Newton but Pascal law should be applied to calculate the compensating flow force.

Abstract: In this paper a proposal aimed at favouring the understanding of fundamentals of hydrostatics, with particular attention to the Pascal principle, is presented. The instruction material was developed in a hypertextual environment and based on a model which explains staticproperties ofliquids. Particularattention is given to the isotropic transmission of forces inside a liquid and to its action on the walls of the container. The model, with appropriate adjustements, can lead to define pressure.