File Name: eulerian and lagrangian description of fluid motion .zip
Tensor Analysis and Continuum Mechanics pp Cite as.
- 5.1: Lagrangian and Eulerian descriptions
- Lagrangian and Eulerian specification of the flow field
- The Lagrangian Picture of Fluid Motion and its Implication for Flow Structures
- Lagrangian and Eulerian Descriptions
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. This essay considers the two major ways that the motion of a fluid continuum may be described, either by observing or predicting the trajectories of parcels that are carried about with the flow — which yields a Lagrangian or material representation of the flow — or by observing or predicting the fluid velocity at fixed points in space — which yields an Eulerian or field representation of the flow. Save to Library.
5.1: Lagrangian and Eulerian descriptions
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Lagrangian and Eulerian specification of the flow field
In classical field theories , the Lagrangian specification of the flow field is a way of looking at fluid motion where the observer follows an individual fluid parcel as it moves through space and time. This can be visualized as sitting in a boat and drifting down a river. The Eulerian specification of the flow field is a way of looking at fluid motion that focuses on specific locations in the space through which the fluid flows as time passes. The Lagrangian and Eulerian specifications of the flow field are sometimes loosely denoted as the Lagrangian and Eulerian frame of reference. However, in general both the Lagrangian and Eulerian specification of the flow field can be applied in any observer's frame of reference , and in any coordinate system used within the chosen frame of reference. These specifications are reflected in computational fluid dynamics , where "Eulerian" simulations employ a fixed mesh while "Lagrangian" ones such as meshfree simulations feature simulation nodes that may move following the velocity field. In the Eulerian specification of a field , the field is represented as a function of position x and time t.
There are two ways to describe the fluid motion. One is called Lagrangian, where one follows all fluid particles and describes the variations around each fluid particle along its trajectory. The other is Eulerian, where the variations are described at all fixed stations as a function of time.
The Lagrangian Picture of Fluid Motion and its Implication for Flow Structures
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Lagrangian and Eulerian Descriptions
We can observe a flow in two ways, first by focusing on the motion of a specific fluid parcel see section 1. These are called the Lagrangian and Eulerian descriptions of flow, respectively. Here we will seek to understand the distinction more fully, to become fluent with both points of view, and to translate between them. Lagrangian information concerns the nature and behavior of fluid parcels. Eulerian information concerns fields , i.
In this chapter, an Euler-Lagrangian double-way coupled model is presented for simulating the liquid particle dispersion ejected from a high-pressure nozzle. This code is the double way coupled with a Lagrangian one-particle model. The theoretical remarks of the double-way coupling, the simulation of the liquid droplet trajectory, and, finally, the droplet collision in the spray cloud using a binary collision model are descripts. The results of droplet velocities and diameters are compared with experimental laboratory measurements. Finally, agrochemical spraying over a cultivated field in weak wind and high air temperature conditions is showed.
New Perspectives in Turbulence pp Cite as. An alternative approach is that of the Lagrangian description, in which the individual particles are marked and followed in a time-dependent way. A time derivative on a given marked particle gives its velocity, and this gives a connection with the Eulerian description mentioned above. The partial differential equations for the Eulerian and Lagrangian schemes look superficially different, but are connected by the ordinary differential equations quoted above. However, there are some phenomena of relevance and importance in connection with turbulence and with transition to turbulence, in which an approach from the Lagrangian point of view gives rise to simpler and less intuitive nonlinear mathematics, and leads to illuminating insights.
Lagrangian statistics and pair dispersion induced by an isolated pulse of a small jellyfish, Aurelia aurita , were quantified and characterized using 3D particle tracking velocimetry 3D-PTV. Probability density functions PDF of the Lagrangian velocity components indicated more intense mixing in the radial direction and revealed three stages dominated by flow acceleration, mixing, and dissipation. Time evolution of the Lagrangian acceleration variance further illustrates each phase. During the mixing phase, the flow shares characteristics of homogeneous isotropic turbulence. In addition, we show that a single pulse may induce rich wake dynamics characterized by pair dispersion with a super-diffusive t 3 regime due to large-scale flow inhomogeneity, followed by a coherent t 2 -Batchelor scaling and then t 1 -Brownian motions. The first trend occurred in the accelerated flow, whereas the second dynamic was observed in the mixed wake and depended on the initial separation.
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