The De Brouckere mean diameter is a concept used in the field of sedimentology and particle size analysis. It is defined as the average diameter of particles in a sediment sample, calculated in such a way that it accounts for the surface area of the particles rather than just their linear dimensions. The De Brouckere mean diameter is often used when studying granular materials or sediments to provide a more accurate depiction of the particle size distribution.
"Dead water" generally refers to a phenomenon observed in maritime navigation, particularly in the context of river or coastal waters. It describes a condition where a body of water becomes unusually still or stagnant, affecting vessel movement. This phenomenon can result from various factors, including: 1. **Density Differences**: Dead water can occur when freshwater from rivers meets saltwater from the ocean.
Detached Eddy Simulation (DES) is a hybrid computational fluid dynamics (CFD) approach used to simulate turbulent flows. It combines elements of both Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) methodologies to effectively model the behavior of turbulence in various flow scenarios, particularly in complex geometries where both attached and detached flow regions can exist.
The Diffuse Element Method (DEM) is a computational technique used primarily for solving partial differential equations (PDEs) in engineering and physics contexts. It is a mesh-free method, meaning it does not require a traditional mesh to discretize the problem domain. Instead, it utilizes a set of scattered points within the domain and interpolates the field variables at these points using diffuse or radial basis functions.
The discharge coefficient (often denoted as \( C_d \)) is a dimensionless number used in fluid dynamics to characterize the flow through an orifice, nozzle, or other flow constrictions. It represents the efficiency of the flow as it passes through a restriction relative to the theoretical flow predicted by Bernoulli's equation.
The Eckert number (Ec) is a dimensionless quantity used in fluid mechanics and heat transfer to characterize the relative importance of thermal energy storage to the convective heat transfer in a flowing fluid. It is defined as the ratio of kinetic energy to thermal energy associated with the temperature changes in the fluid.
The term "effusive limit" usually pertains to the context of volcanic activity. It refers to the boundary or threshold at which magma begins to flow out of a volcano in a relatively non-explosive manner, resulting in an effusive eruption. These eruptions typically produce lava flows instead of explosive ash clouds, and they occur when the viscosity of the magma is low enough to allow it to flow freely.
The Ekman number (Ek) is a dimensionless quantity in fluid dynamics that characterizes the relative importance of the viscous forces to the Coriolis forces in a rotating fluid system.
The Elsasser number (Λ) is a dimensionless parameter used in magnetohydrodynamics (MHD) to characterize the relative significance of magnetic forces compared to viscous forces in a conducting fluid. It is defined as the ratio of the magnetic pressure to the viscous stress in the fluid.
In hydrodynamics, "entrainment" refers to the process by which a fluid (such as water) picks up and incorporates small volumes of another fluid (or gas) or particles from its surroundings. This phenomenon is commonly observed in various natural and engineered systems, including rivers, ocean currents, and industrial processes.
Estuarine Turbidity Maximum (ETM) refers to a specific area within an estuary where the concentration of suspended sediments, primarily fine particles and organic matter, is significantly higher than in surrounding waters. This phenomenon typically occurs due to the interaction of freshwater from rivers and saltwater from the ocean, leading to various physical and biological processes.
Extensional viscosity is a measure of a fluid's resistance to deformation under extensional (stretching) flow conditions. Unlike shear viscosity, which describes a fluid's resistance to flow when layers slide past one another, extensional viscosity relates to how the fluid behaves when it is being stretched or elongated. In extensional flow, a fluid element experiences forces that cause it to be pulled apart, creating a change in shape without necessarily changing volume.
External flow refers to the movement of fluid (usually air or water) over the surface of an object that is not enclosed within the fluid. This concept is commonly used in fields like fluid mechanics, engineering, and aerodynamics, where it is important to understand how fluids interact with solid boundaries.
In the context of aircraft navigation and aerodynamics, the term "F-plane" refers to a specific type of reference plane used in flight dynamics and control theory. It is typically part of the formulation of aircraft equations of motion. The F-plane is aligned with the flight path of the aircraft and is used to analyze how the aircraft responds to various forces and moments during flight.
"Flow conditions" can refer to different contexts depending on the field of study or application, such as fluid dynamics, project management, or even psychology. Below are explanations of flow conditions in a few relevant areas: 1. **Fluid Dynamics**: In this context, flow conditions refer to the characteristics of a fluid in motion. This can include factors such as velocity, pressure, density, temperature, and viscosity.
Flow meter error refers to the discrepancy between the measured flow rate as indicated by a flow meter and the actual flow rate of a fluid passing through the meter. This error can arise from various factors, including: 1. **Calibration Error**: If the flow meter is not properly calibrated, it may provide inaccurate readings. Regular calibration is necessary to ensure accuracy. 2. **Installation Effects**: Poor installation can lead to errors.
Flux-Corrected Transport (FCT) is a numerical method used in computational fluid dynamics and other fields for the transport of scalar quantities, such as mass, energy, or chemical concentration, in a spatial domain. The method is particularly useful when dealing with convection-dominated problems, where the transport process can exhibit steep gradients or sharp fronts, such as in the advection of a pollutant in a fluid or the evolution of a shock wave.
Force density is a physical concept often used in fields like physics and engineering, particularly in the context of continuum mechanics and material science. It is defined as the force per unit volume applied to a material or system. In mathematical terms, force density \(\mathbf{f}\) is expressed as: \[ \mathbf{f} = \frac{\mathbf{F}}{V} \] where \(\mathbf{F}\) is the total force acting on the volume \(V\).
Free molecular flow refers to a regime of gas flow where the mean free path of gas molecules is much larger than the characteristic dimensions of the system through which the gas is flowing. In this condition, gas molecules travel between collisions without interacting with other molecules, often behaving as if they are in a vacuum. ### Key Characteristics of Free Molecular Flow: 1. **Mean Free Path**: This is the average distance a molecule travels between successive collisions.