A mathematical model for type II profile of concentration distribution in turbulent flows

2016 ◽  
Vol 17 (3) ◽  
pp. 449-472
Author(s):  
Snehasis Kundu ◽  
Koeli Ghoshal
Keyword(s):  
Mathematical Model ◽  
Turbulent Flows ◽  
Concentration Distribution ◽  
Type Ii

State Estimator of Flow as an Integrated Computational Method With the Feedback of Online Experimental Measurement

1997 ◽  
Vol 119 (4) ◽  
pp. 814-822 ◽  
Author(s):  
Toshiyuki Hayase ◽  
Satoru Hayashi
Keyword(s):  
Mathematical Model ◽  
Turbulent Flows ◽  
Experimental Measurement ◽  
Flow Simulation ◽  
Computational Method ◽  
Feedback Gain ◽  
State Estimator ◽  
Output Measurement ◽  
Real Flow ◽  
The Mathematical Model

This paper deals with a state estimator or simply an observer of flow field. The observer, being a fundamental concept in the control system theory, also has a potential in the analysis of flow related problems as an integrated computational method with the aid of experiment. In the framework of the observer, the state of physical flow is estimated from the mathematical model with the feedback of on-line experimental measurement. A SIMPLER based flow simulation algorithm is used as the mathematical model of the real flow and partial experimental measurement of flow is fed back to the boundary condition through the feedback controller. The existence of the feedback-loop essentially distinguishes the observer from ordinary flow simulations. Time variation of the computational result of the observer is expected to converge exactly to that of the physical flow in the whole flow domain even for unstable turbulent flows. A numerical experiment has been performed to confirm the validity of the proposed observer for a turbulent flow through a duct of square cross section. The physical flow to be estimated is modeled by a numerical solution. Appropriate choice for the proportional feedback gain of the observer results in accelerated convergence of the simulation by a factor of 0.012 and reduced error in estimation of the perturbation velocity by a factor of 0.6 in the whole domain or a factor of 0.3 behind the output measurement plane in comparison with the ordinary flow simulation without feedback.

Computations of Three-Dimensional Gas-Turbine Combustion Chamber Flows

1979 ◽  
Vol 101 (3) ◽  
pp. 326-336 ◽  
Author(s):  
M. A. Serag-Eldin ◽  
D. B. Spalding
Keyword(s):  
Mathematical Model ◽  
Turbulent Flows ◽  
Combustion Process ◽  
Three Dimensional ◽  
Solution Algorithm ◽  
Physical Models ◽  
Turbulence Energy ◽  
Experimental Conditions ◽  
Diffusion Controlled ◽  
The Mathematical Model

The paper presents a mathematical model for three-dimensional, swirling, recirculating, turbulent flows inside can combustors. The present model is restricted to single-phase, diffusion-controlled combustion, with negligible radiation heat-transfer; however, the introduction of other available physical models can remove these restrictions. The mathematical model comprises differential equations for: continuity, momentum, stagnation enthalpy, concentration, turbulence energy, its dissipation rate, and the mean square of concentration fluctuations. The simultaneous solution of these equations by means of a finite-difference solution algorithm yields the values of the variables at all internal grid nodes. The prediction procedure, composed of the mathematical model and its solution algorithm, is applied to predict the fields of variables within a representative can combustor; the results are compared with corresponding measurements. The predicted results give the same trends as the measured ones, but the quantitative agreement is not always acceptable; this is attributed to the combustion process not being truly diffusion-controlled for the experimental conditions investigated.

Numerical Simulation of Plug Discharge with Dissolved Oxygen Convection and Diffusion

2012 ◽  
Vol 433-440 ◽  
pp. 1920-1925
Author(s):  
Ze Gao Yin ◽  
Le Wang ◽  
Jin Xiong Zhang ◽  
Xian Wei Cao
Keyword(s):  
Mathematical Model ◽  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Dissipation Rate ◽  
Concentration Distribution ◽  
Coupled Model ◽  
Computational Results ◽  
Dissolved Oxygen Concentration ◽  
Velocity Pressure ◽  
And Diffusion

In Fluent, the 3-D RNG k- ξ mathematical model is employed to compute the plug discharge, and dissolved oxygen convection and diffusion model is established to simulate the concentration distribution of dissolved oxygen with user defined scalar method. Velocity, pressure, turbulence kinetic energy, turbulence dissipation rate and dissolved oxygen concentration are computed. Then, velocity, pressure and dissolved oxygen concentration are compared with the data of physical model, and they agree with each other approximately, showing it is valid and reliable to compute the plug discharge and dissolved oxygen concentration with the coupled model. Furthermore, the characteristics of hydraulic factors including dissolved oxygen concentration are analyzed and generalized based on the computational results.

Calculations of three-dimensional viscous flow in a multiblade centrifugal fan by modelling blade forces

2003 ◽  
Vol 217 (3) ◽  
pp. 287-297 ◽  
Author(s):  
S-J Seo ◽  
K-Y Kim ◽  
S-H Kang
Keyword(s):  
Mathematical Model ◽  
Turbulent Flows ◽  
Numerical Study ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Centrifugal Fan ◽  
Complex Flows ◽  
Flow Through ◽  
Volume Method ◽  
The Mathematical Model

A numerical study is presented for Reynolds-averaged Navier-Stokes analysis of three-dimensional turbulent flows in a multiblade centrifugal fan. Present work aims at development of a relatively simple analysis method for these complex flows. A mathematical model of impeller forces is obtained from the integral analysis of the flow through the impeller. A finite volume method for discretization of governing equations and a standard k-ɛ model as turbulence closure are employed. For the validation of the mathematical model, the computational results for velocity components, static pressure, and flow angles at the exit of the impeller were compared with experimental data. The comparisons show generally good agreement, especially at higher flow coefficients.

Dissolved Oxygen Convection and Diffusion Numerical Simulation of Water and Air Mixture Flow in Circular Pipe

2011 ◽  
Vol 383-390 ◽  
pp. 6651-6656
Author(s):  
Ze Gao Yin ◽  
Xian Wei Cao ◽  
Dong Sheng Cheng ◽  
Le Wang
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Pipe Flow ◽  
Concentration Distribution ◽  
Dissolved Oxygen Concentration ◽  
Mixture Flow ◽  
Velocity Pressure ◽  
And Diffusion

In Fluent, the 3-D RNG k–ε mathematical model is employed to compute water and air mixture pipe flow. The dissolved oxygen convectionaεnd diffusion model is established to simulate the concentration distribution of dissolved oxygen with user defined scalar method. Velocity, pressure and dissolved oxygen concentration are computed. Then, dissolved oxygen concentration and pressure are compared with the data of physical model, and they agree with each other approximately, showing it is valid and reliable to compute the mixture pipe flow and dissolved oxygen concentration with the model .Furthermore, under a specific condition, velocity, pressure and dissolved oxygen concentration of water and air mixture pipe flow are computed and their characteristics are analyzed.

Three-Dimensional Sediment Numerical Simulation of Wenzhou Oufei Tidal Flat Sea Area

2012 ◽  
Vol 535-537 ◽  
pp. 1775-1779
Author(s):  
Jia Rui Li ◽  
Lei Mo ◽  
Wen Hu Zhang
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Tidal Flat ◽  
Concentration Distribution ◽  
Three Dimensional ◽  
Sediment Concentration ◽  
Basic Law ◽  
Open Sea ◽  
Calculation Results ◽  
Sea Area

A flow and sediment mathematical model was built under three-dimensional hybrid coordinate to simulate Wenzhou Oufei tidal flat and its neighboring sea area, and the verification was down. The calculation results and the observed data are identical well. In estuary area, the sediment concentration is the highest, then outside the estuary. In Oufei tidal flat area, the sediment concentration is relatively high, and it decreases gradually towards the open sea. Through the simulation, the characteristics and the basic law of sediment concentration distribution was reproduced.

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