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Published in Jan van ‘t Hoff, Art Nooy van der Kolff, Hydraulic Fill Manual, 2012
Jan van ‘t Hoff, Art Nooy van der Kolff
It follows that the values of ground acceleration show a high variation even within small regions. This is especially true for medium- to large-size earthquakes and interpolating the values is thus difficult. Generally the acceleration will decrease the further away from the fault. The calculation of the Peak Ground Acceleration (PGA) is based on horizontal ground movements. The acceleration is expressed as a decimal or percentage of the Earth’s gravitational acceleration, g = 9.81 m/s2. The PGA is often used in the design specifications of reclamation projects and usually based on (local) Building Codes and experience. The analysis of the liquefaction potential and stability of earth structures is generally based on the PGA (see also section 8.6.4.2).
Dynamics of impacts
Published in Ömer Aydan, Rock Dynamics, 2017
When the object is released, the vertical acceleration reaches gravitational acceleration and it remains the same during free-fall as expected. The maximum ground acceleration occurs during impact and the generated wave form is not symmetric. The ground acceleration at a distance of R/a = 4.3 is about 0.6–0.72G and its wave form is symmetric. From the experimental results, it seems that the following expression holds: mamax=(m+M)ag
Motion of bodies
Published in Anthony Johnson, Keith Sherwin, Foundations of Mechanical Engineering, 2017
Anthony Johnson, Keith Sherwin
A huge mass such as the earth attracts other masses such as cars, bricks, people, etc. and makes them stay on the earth’s surface. If objects are allowed to fall, they will accelerate at a constant rate, termed the gravitational acceleration and designated by g. This is the constant acceleration due to gravitational attraction. The gravitational value g varies at different points on the earth’s surface but it is generally taken to be 9.B1 m/s2.
Study of a Falling Rigid Particle Passing Around Obstacles in a Fluid Channel
Published in International Journal of Computational Fluid Dynamics, 2020
Kamran Usman, Jabbar Ali, Rashid Mahmood, Sardar Bilal, Saqia Jabeen, Junaid Asmat
We have examined the behaviour of a falling particle inside a vertical channel passing across two internal circular cylinders. When the falling particle crosses the cylinders, it disturbs the pressure field and consequently disturbs the fluid motion as well as the hydrodynamic drag and lift forces acting on the surface of cylinders. The disturbance propagates further towards the second cylinder while particle passes through the first cylinder and results in different patterns for fluid and particle motion. The collisions and overlapping of particle with cylinders and with the outer wall are avoided using collision models discussed in Equation (9) and Equation (10). The width and height of the computational channel is 0.41 and 2.5, respectively as shown in Figure 2(a). The moving rigid 2D particle has density . Density of incompressible fluid is taken and the Reynolds number is Re = 100. In numerical simulations, we consider the particle of radius R = 0.05. We consider that initially at t = 0 the fluid and particle are both at rest. The falling motion is started only due to the gravitational acceleration . Zero dirichlet boundary conditions at the walls of the channel are assumed. The simulations are performed on fixed equidistant meshes using CFD code FEATFLOW (Turek 1998).
Numerical investigation of driving forces in a geyser event using a dynamic multi-phase Navier–Stokes model
Published in Engineering Applications of Computational Fluid Mechanics, 2018
Dam-break simulation is a benchmark problem for two-phase flow models due to the simple initial and boundary conditions. Dam break problems involve significant interface deformation such as overturning, breaking up and air entrapment. The interface dynamics are a challenge to some two-phase models. The experimental work of Martin and Moyce (1952) is commonly used to check the numerical results. In the dam break problem, initially a rectangular column of still water is contained between a vertical wall and a gate. At time t= 0+, the gate is suddenly removed and the water column starts collapsing under gravity. This collapsed water column forms an advancing water wave, propagating to the right. The numerical computational domain size is the same as Martin and Moyce's experiments (1952), which is a square of 4a× 4a, where a is the initial water column width. The initial water column is 0.05175 m (a) wide and 0.1035 m (2a) tall. The densities of water and air used in the simulation are 1000 kg/m3 and 1.23 kg/m3, respectively. Viscosities for water and air are 1.0 × 10−3 kg/m·s and 1.8 × 10−5 kg/m·s, respectively. The gravitational acceleration is 9.8 m/s2. The grid size is 64 by 64 with a time step size of 5 × 10−5 sec. A non-slip boundary condition is used for the two vertical walls and the bottom boundary. The top boundary is open.
Enhanced Temperature Stratification with Deflectors Laid within the Horizontal Water Storage Tank
Published in Heat Transfer Engineering, 2022
Yunze Shen, Jin-yuan Qian, Leilei Fan, Zhilin Sun, Bengt Sundén
Before the solar water heating system is exposed to the solar irradiance, the water inside the system has a uniform temperature distribution as initial condition and a static velocity field is assumed. The ambient temperature is equal to the initial water temperature before the natural convection process begins. The gravitational acceleration is given as 9.8 m/s2. The domain walls have a no-slip momentum boundary condition. The tank surfaces are adiabatic surfaces, which suggests that the heat transfer coefficient of the water storage tank surface is 0.6 W/m2K.