Ideal fluids are used to model the behavior of fluids both in motion and at rest. Which one of the following assumptions does NOT apply to an ideal fluid?

Question

Ideal fluids are used to model the behavior of fluids both in motion and at rest.  Which one of the following assumptions does NOT apply to an ideal fluid?

Quizplus · Accepted Answer

11ecba2d_131f_36e3_a3bf_c9ca68bf0771_MD0008_00 Fluids are substances that have no fixed shape and readily conform to the dimensions of the container in which they are placed. Fluids that are considered ideal share the following attributes: No viscosity: Friction between fluid molecules is negligible such that applied shearing forces (ie, gravity acting on a fluid pouring out of a glass) cause instantaneous, uniform acceleration of the fluid (Choice C). Laminar flow: The fluid flows in parallel layers, each with equal velocity. No interaction between each layer occurs, ensuring uniform velocity within the fluid at all points (Choice A). Incompressible: The density of the fluid is modified by neither external forces nor its own weight when oriented in a fluid column (Choice D). Ideal fluid behavior serves as a model for many practical applications of fluids. For example, water and mercury are both relatively incompressible, which allows both fluids to be used within a simple fluid barometer to reliably measure atmospheric pressure (P_atm). Furthermore, ideal fluid behavior is essential for the application of Bernoulli's equation, which mathematically describes the conservation of energy in fluids in terms of fluid pressure (P), density (ρ), and velocity (v) between two points (A and B) within a conduit (ie, the container through which a fluid flows): 11ecba2d_131f_36e4_a3bf_0b1349274ff4_MD0008_00 Bernoulli's equation predicts changes in fluid flow and pressure that occur following a change in fluid height (h) or conduit geometry. For example, Bernoulli's equation dictates that the pressure of an ideal fluid will decrease as fluid velocity increases and the height remains constant. Consequently, changes in fluid kinetic energy must be accompanied by changes in pressure energy so that overall energy is conserved. Therefore, the statement that fluid pressure is not influenced by fluid velocity is not true for an ideal fluid. Educational objective: Ideal fluids are totally nonviscous and incompressible; they exhibit smooth, laminar flow without viscosity. Bernoulli's equation dictates that an increase in the velocity of an ideal fluid is accompanied by a decrease in fluid pressure.

Ideal Fluids Are Used to Model the Behavior of Fluids