Evaluation Of Boundary Conditions Research Articles

Research on support vector machine method for comprehensive evaluation after compression

Hydraulic fracturing is one of the important measures to increase production of oil and gas reservoirs. Pressure after the assessment of the existing technology is usually divided into direct and indirect diagnosis of hydraulic fracture. The diversity of evaluation results is due to the uncertainty and immaturity of the technology itself. Up to now, we have not found an economical and accurate hydraulic fracture evaluation method in the development and application of fracturing technology. In this paper, the pressure treatment technology after the comprehensive evaluation of boundary conditions is studied. By introducing the support vector regression theory, an evaluation model and a solution for correcting fracturing parameters are proposed. Fracturing parameters include fracture length, fracture height, fracture width, integrated fracturing fluid leakage coefficient, fracture conductivity, fracture closure pressure, and so on. For the optimization of various parameters, objective and scientific comprehensive evaluation results can be obtained by selecting different kernel functions. The results show that the model and method based on support vector machine are effective and practical.

Evaluation of Boundary Conditions for CFD Simulation of Liquid Food Thermal Process in Glass Bottles

The growing demand for safer and high-quality food products creates the need for better knowledge of the processes involved in food production. The computational fluid dynamics (CFD) have been widely used to better understand food thermal process, one of the safest and most frequently used methods for food preservation. However, no consistency in mathematical models has been observed, especially on the boundary conditions definition. The present study has evaluated four methodologies for the definition of boundary conditions for heating water in two commercial bottles: (M1) temperature profile of heating water (T∞) and convective heat transfer coefficient (h), (M2) T∞ as boundary condition for the outside package wall, (M3) T∞ as boundary condition for the outside heated liquid edge, and (M4) internal temperature profile (T=T(x,y,z,t)), previously measured in the inner package wall, as boundary condition for the outside heated liquid edge. Models that considered the measured value of h e T∞ as boundary condition showed good agreement with experimental values, compared by thermal history and sterilization value (F). The models that considered the temperature profile of the heating water or the inner package wall as boundary conditions, showed faster heating. By over-estimating the product heating rate, those models are not appropriated for thermal process modelling, as it compromises the safety and preservation of food products.

In-Situ Load Testing: A Theoretical Procedure to Design a Diagnostic Cyclic Load Test on a Reinforced Concrete Two-Way Slab Floor System

The objective of this paper is to showcase to an engineer who is considering performing a diagnostic cyclic load test a theoretical procedure for determining the patch load, which when applied to a two-way reinforced concrete (RC) slab floor system would generate internal forces at critical locations equal to those resulting from the uniformly distributed load. This procedure should also help the practitioner to define a representative model of the structure and to update the magnitude of the target load at the end of each loading and unloading cycle by means of a real-time evaluation of boundary conditions and slab stiffness. The routine to design a cyclic load test is described theoretically first and then validated with the results of a load test on a concrete two-way RC slab floor system. Introduction The current role of testing within structural engineering has gained increasing importance, as it can now be applied to every phase of the structure’s life because of innovative materials and new design approaches. By focusing on either the preliminary testing of a new structure or the necessary control checks prior to assessing the strength of an existing one, in-situ load testing can determine the real behavior of the structure under the existing loading conditions. Accordingly, researchers can have an overall, accurate understanding of the mechanical properties of the structural members. In the United States of America, the current American Concrete Institute (ACI) 318 Building Code [1] provides requirements for load testing of concrete structures. ACI Committee 437 [2] proposes a diagnostic cyclic load (DCL) testing procedure consisting of the application of patch loads in a quasi-static way to the structural member according to loading and unloading cycles. Patch load magnitude and distribution shall simulate the uniformly distributed load defined in the ACI 318 Building Code. The DCL protocol [3,4] defines three acceptance criteria that can be easily computed, in real time, for any structural member by simply checking its behavior under the test load (see Fig. 1 for necessary notation). Repeatability and Permanency represent the behavior of the structure during two identical load cycles; Deviation from linearity represents the measure of the nonlinear behavior of a member being tested. Repeatability = 100 95 B B max r A B max r % % Δ − Δ × ≥ Δ − Δ ; (1) Permanency = 100 10 B r B max % % Δ × ≤ Δ ; (2)

Evaluation of boundary conditions used to model dilute, turbulent gas/solids flows in a pipe

A turbulent gas/solids model, based on the work of Simonin [1] [Simonin, O., 1996. Continuum modeling of dispersed two-phase flows, in Combustion and Turbulence in Two-Phase Flows, Von Karman Institute of Fluid Dynamics Lecture Series 1996-2], has been recently implemented in the MFIX computational fluid dynamic (CFD) code. This theory includes the effects of turbulence in the gas phase as well as inter-particle collisions. The extension of this theory [2] [Balzer, G., Simonin, O., Boelle, A., Lavieville, J., 1996. A unifying modelling approach for the numerical prediction of dilute and dense gas-solid two phase flow, CFB5, 5th Int. Conf. on Circulating Fluidized Beds, Beijing, China] to dense gas/solids systems was made possible by including the kinetic theory of granular material to describe the solids stresses. The turbulence model and boundary conditions were evaluated by simulating the gas/solids flow experiments of Jones [3] [N.E. Jones, An experimental investigation of particle size distribution effect in dilute phase gas–solid flow, Ph.D. thesis, Purdue University (2001)]. Their experimental results included velocity and turbulence measurements for fully developed flows for a range of particle loading from very dilute to relatively dense. Our numerical calculations were conducted by imposing periodic boundary conditions as well as in a long pipe with different length-to-diameter ratios to achieve a fully developed condition. We propose modifications to the single-phase wall functions, to include the effect of the particulate phase. However, these modifications had only a minor effect on the predictions of gas turbulent kinetic energy due to the dilute nature of the flow considered in this study. The turbulent gas/solids flow model based on the work of Simonin [1] [Simonin, O., 1996. Continuum modeling of dispersed two-phase flows, in Combustion and Turbulence in Two-Phase Flows, Von Karman Institute of Fluid Dynamics Lecture Series 1996-2] is able to predict reasonably well dilute gas/solids flows with appropriate boundary conditions (BC). Four different types of boundary conditions were investigated to assess their sensitivity. The experimental data fall between the large-friction/no-sliding and small-friction/all-sliding limits of Jenkins and Louge [4] [J.T. Jenkins, M.Y. Louge, On the flux of fluctuating energy in a collisional grain flow at a flat frictional wall, Phys. Fluids 9 (10), (1997) 2835–2840] BC. However, the physical behavior of the particle–wall interactions is close to the small-friction/all-sliding limit of Jenkins and Louge BC or the Johnson and Jackson [5] [P.C. Johnson, R. Jackson, Frictional-collisional constitutive relations for granular materials, with application to plane shearing. J. Fluid Mech. 176 (1987) 67–93]BC with a small specularity coefficient or simply the free-slip BC.

411 Image-Based Simulation における境界条件の検討

411 Image-Based Simulation における境界条件の検討

A new nutation series for a more realistic model earth

SUMMARY The frequency-dependent correction coefficients with respect to the forced nutations of a rigid earth are computed using the complex scalar gravitational-motion equations for an earth model with an anelastic mantle. Oceanic loads and tidal currents enter the model via outer boundary conditions. The ellipticity of the core-mantle boundary and the dynamical ellipticity are adjusted to observations. This requires the behaviour inside the model earth to be regarded as non-hydrostatic. Some relevant equations for the evaluation of boundary conditions and some terms in the equations of motion are expanded to second order in ellipticity. The computation of the equipotential-surface ellipticity profile is carried to second order as well. These second-order expansions lead to increased accuracy of the results in general. Moreover, one achieves a better reliability for the integration at frequencies close to a resonance. This allows the integration of the equations of motion at any relevant nutation period without the need for a normal-mode expansion. A complete new nutation series for a realistic model earth is presented.

Evaluation of boundary conditions for a mathematical model of heat transfer in a glass furnace

The results of a thermal engineering analysis of a bath furnace heated by natural gas with the surface area of the melting part equal to 303.3 m2 and equipped with six pairs of burners are presented. Practical recommendations are given for increasing the efficiency of the furnace. The data can be used for developing a mathematical model of heat transfer in a glass furnace.

High‐order axisymmetric Navier–Stokes code: Description and evaluation of boundary conditions

AbstractA description is given of a high‐order solution algorithm for the solution of the unsteady axisymmetric Navier–Stokes equations. The method consists of a combination of fourth‐order and second‐order accurate finite difference schemes, where the approximated equations are solved by an alternating direction implicit (ADI) method. Special attention is paid to the boundary conditions. Results are compared with measurements for the cases of rotating flow within a closed cylinder (rotating driven cavity), developing axial flow in a stationary pipe and developing flow in a rotating pipe.