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Blood Flow Mechanics
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
In case of blood flow, the only applied body force is normally due to gravity, equaling ρg; however, for particular cases, other body forces may need to be considered. For example, if the referential frame is accelerating, the force that results from the acceleration of the reference frame must also be considered. Examples of these so-called fictitious forces include the centrifugal force that acts on blood cells during a centrifugation process and the “g-force” that results from the sudden acceleration of a fighter jet, pushing blood away from the pilot’s head. The surface forces account for normal and tangential forces and include pressure and viscous forces.
Multiphysics in molecular dynamics simulation
Published in Ken P. Chong, Arthur P. Boresi, Sunil Saigal, James D. Lee, Numerical Methods in Mechanics of Materials, 2017
James D. Lee, Jiaoyan Li, Zhen Zhang, Kerlin P. Robert
To capture the full motion of a material body with respect to a noninertial reference frame (a reference frame accelerates and rotates), the governing equation must account for the motion of the reference frame itself; thus, fictitious forces are introduced. Rectilinear acceleration force, centrifugal force, Coriolis force, Euler force, etc., are several commonly noticed fictitious forces. Moreover, Einstein pointed out that gravity, too, is a form of fictitious force, which leads to the birth of general relativity. It is regarded that the appearance of fictitious force resolves the discrepancy in different noninertial reference frames so that motion observed in one frame can be converted to the motion observed in another. As one has already observed that acceleration a ≡ v˙ is not objective (cf. Equation 8.49), let i be the acceleration induced by the fictitious force and principle of objectivity imposes a requirement
Continuous Models for Vibration: Advanced Models
Published in Haym Benaroya, Mark Nagurka, Seon Han, Mechanical Vibration, 2017
Haym Benaroya, Mark Nagurka, Seon Han
The centrifugal and Coriolis forces are sometimes called fictitious forces as they are not external applied forces. The centrifugal force is due to rotational motion and the Coriolis force is present when a body undergoes motion relative to a rotating coordinate system.
Estimation in jet deflection angle of deflector on the chutes
Published in ISH Journal of Hydraulic Engineering, 2023
When the Froude number increases from 3.0 to 6.6, the tangent value of deflection angle decreases by about 48%, and the deflection angle decreases by about 8°. However, in the study of flip bucket or aerators on spillways, the takeoff angle of jet is positively correlated with Froude number universally (Rutschmann and Hager 1990; Heller V et al. 2007; Steiner et al. 2008). The impact of fictitious force becomes more prominent with the increase of Froude number, and the effect of gravity reduces accordingly. In this case, the flip bucket could overcome gravity more easily to generate the jet, while on the other hand， it is more difficult for deflector to change flow direction as fictitious force increases. As a result, the variations of deflection angle and takeoff angle with Freund number are completely opposite. Under flow condition of high Froude number, the function of the deflector was weakened, and the deflection angle gradually decreased.
A Numerical Based Parametric Study on Seismic Amplifications Due to Soft Deposits on Seabed
Published in Journal of Earthquake Engineering, 2022
Víctor Martínez Calzada, Pablo Arizpe Carreón, Jovan Basaldúa Sanchez, Alejandro Rodríguez Castellanos
Furthermore, pressure in fluids can be given by the Green function . Here, is Hankel’s function of second kind and zero order, is the distance between and , is the sound velocity in the fluid. Our proposal is to represent the pressure field as a scalar field in terms of the Green function () and a fictitious force density (). Hence, pressures and displacements in the fluid can be obtained from:
A review on modelling ground vibrations generated by underground trains
Published in International Journal of Rail Transportation, 2019
Another analytic 3D model is based on the wave number fictitious force approach, reported in Ref [38] (see Fig. 6). in which ground vibration generated by a harmonic load moving in a circular tunnel in a horizontally layered ground is investigated. In this model, moving Green’s functions for a layered half-space [39] and those for a circular layered cylinder of infinite length [40] are employed to establish boundary integral equations governing unknown fictitious forces (stresses) and tunnel–soil interaction stresses. The tunnel must be embedded totally in a single layer of soil. The boundary integral equations only require the displacement of Green’s functions rather than both displacement and traction Green’s functions that are required by the conventional boundary integration technique (as in Ref [36].). This advantage is achieved by the introduction of the excavated cylinder into consideration. By expressing the Green’s functions and other terms in terms of a Fourier series (since the tunnel is circular), the boundary integral equations are transformed into a set of algebraic equations from which the unknowns can be determined.