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About: Inflow is a(n) research topic. Over the lifetime, 9752 publication(s) have been published within this topic receiving 105378 citation(s).
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Journal ArticleDOI
T. S. Lund1, Xiaohua Wu1, Kyle D. Squires1Institutions (1)
Abstract: A method for generating three-dimensional, time-dependent turbulent inflow data for simulations of complex spatially developing boundary layers is described. The approach is to extract instantaneous planes of velocity data from an auxiliary simulation of a zero pressure gradient boundary layer. The auxiliary simulation is also spatially developing, but generates its own inflow conditions through a sequence of operations where the velocity field at a downstream station is rescaled and re-introduced at the inlet. This procedure is essentially a variant of the Spalart method, optimized so that an existing inflow?outflow code can be converted to an inflow-generation device through the addition of one simple subroutine. The proposed method is shown to produce a realistic turbulent boundary layer which yields statistics that are in good agreement with both experimental data and results from direct simulations. The method is used to provide inflow conditions for a large eddy simulation (LES) of a spatially evolving boundary layer spanning a momentum thickness Reynolds number interval of 1530?2150. The results from the LES calculation are compared with those from other simulations that make use of more approximate inflow conditions. When compared with the approximate inflow generation techniques, the proposed method is shown to be highly accurate, with little or no adjustment of the solution near the inlet boundary. In contrast, the other methods surveyed produce a transient near the inlet that persists several boundary layer thicknesses downstream. Lack of a transient when using the proposed method is significant since the adverse effects of inflow errors are typically minimized through a costly upstream elongation of the mesh. Extension of the method for non-zero pressure gradients is also discussed.

1,341 citations

01 Jan 1978-
Abstract: 1. Some Basic Concepts in Reservoir Engineering. 2. PVT Analysis for Oil. 3. Material Balance Applied to Oil Reservoirs. 4. Darcy's Law and Applications. 5. The Basic Differential Equation for Radial Flow in a Porous Medium. 6. Well Inflow Equations for Stabilized Flow Conditions. 7. The Constant Terminal Rate Solution of the Radial Diffusivity Equation and its Application to Oilwell Testing. 8. Real Gas Flow: Gas Well Testing. 9. Natural Water Influx. 10. Immiscible Displacement. Indexes. Exercises.

1,196 citations

Journal ArticleDOI
Abstract: In contrast to time-evolving turbulence, direct numerical or large eddy simulations of spatially inhomogeneous flows require turbulent inflow boundary conditions, that make the results strongly influenced by the velocity profiles to be prescribed. This paper aims to present a new approach for generating artificial velocity data which reproduces first and second order one point statistics as well as a locally given autocorrelation function. The method appears to be simple, flexible and more accurate than most of the existing methods. This is demonstrated in two cases. First, direct numerical simulations of planar turbulent jets in the Reynolds number range from 1000 to 6000 are performed. Because of the importance of the primary breakup mechanism of a liquid jet in which inflow influences are evident, the new procedure is secondly used, to study atomization in dependence of the flow inside the nozzle by means of a Volume of Fluid scheme.

979 citations

Journal ArticleDOI
John T. Finn1Institutions (1)
TL;DR: Three simple ecosystem models are examined to demonstrate the utility of measures derived from the application of economic input-output analysis to ecosystem compartment models in explaining ecological phenomena.
Abstract: Several measures of ecosystem structure and function are derived from the application of economic input-output analysis to ecosystem compartment models. Total system throughflow (TST) is defined as the sum of all compartmental throughflows. Average path length of the i th inflow (APL 1 ) is defined as the average number of compartments through which the i th inflow passes. Average path length for an average inflow (ĀPL) is the mean of APL 1 weighted according to size of the inflows. ĀPL is shown to be equal to TST divided by the sum of all inflows. TST can be partitioned into a portion due to cycled flow (TST o ) and a portion due to flow straight through the system (straight throughflow, TST s ). The portion of ĀPL due to cycled flow divided by the portion due to straight throughflow is the cycling index (CI). This index indicates how many times further than the straight throughflow path length an average system inflow will travel because of cycling. Three simple ecosystem models are examined to demonstrate the utility of these measures in explaining ecological phenomena.

756 citations

Journal ArticleDOI
Abstract: Statistics obtained from seven different direct numerical simulations (DNSs) pertaining to a canonical turbulent boundary layer (TBL) under zero pressure gradient are compiled and compared. The considered data sets include a recent DNS of a TBL with the extended range of Reynolds numbers Reθ = 500–4300. Although all the simulations relate to the same physical flow case, the approaches differ in the applied numerical method, grid resolution and distribution, inflow generation method, boundary conditions and box dimensions. The resulting comparison shows surprisingly large differences not only in both basic integral quantities such as the friction coefficient cf or the shape factor H12, but also in their predictions of mean and fluctuation profiles far into the sublayer. It is thus shown that the numerical simulation of TBLs is, mainly due to the spatial development of the flow, very sensitive to, e.g. proper inflow condition, sufficient settling length and appropriate box dimensions. Thus, a DNS has to be considered as a numerical experiment and should be the subject of the same scrutiny as experimental data. However, if a DNS is set up with the necessary care, it can provide a faithful tool to predict even such notoriously difficult flow cases with great accuracy.

616 citations

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Topic's top 5 most impactful authors

David A. Peters

37 papers, 1.1K citations

Lance Manuel

11 papers, 185 citations

Haavard Aakre

10 papers, 102 citations

Ewald Krämer

10 papers, 114 citations

Thorsten Lutz

7 papers, 104 citations