I. Szczygieł

Inverse Convection-Diffusion Problem of Estimating Boundary Velocity Based on Internal Temperature Measurements

Possibility and algorithm of identification of boundary velocity based on the measurements of internal temperature is presented and studied in the paper. Procedure for solving the steady state inverse convection-diffusion heat transfer problem with potential fluid flow in 2D was worked out. The presented procedure employs sensitivity coefficient technique and finite element method. Due to the nonlinearity, the iterative algorithm was used for solving the inverse problem. The direct and inverse procedures and their solutions are discussed in the paper. The sensitivity of the estimation with respect to changes of selected parameters is also investigated. The presented analysis is directed at heat transfer processes in the ground with groundwater flow.

Identification of the boundary surfaces in 3D finite element codes

Abstract For a given 3D FEM net defined by a domain connectivity array a boundary connectivity array is generated. The latter contains boundary nodes over which subsequent boundary elements are spanned. An algorithm can be used to check the consistency of the input connectivity array. It can also be useful in pre and postprocessors in hidden lines removal. A list of appropriate routines is included.

Identification of the boundary curves in 2D finite elements codes

Abstract A simple algorithm for identification of the discretized curves bounding 2D regions is described. For a given FEM net defined by the (domain) nodal connectivity array, a boundary nodal connectivity array is generated. The latter contains subsequent boundary elements defined by nodes lying on the boundaries. Boundary elements are grouped into closed contours forming the curves bounding the region under consideration. The algorithm leads to substantial savings in data preparation time. It can also be used to check the consistency of the input connectivity array. A list of appropriate routines is included.

Verification of heat phenomena during surfacing using a thermal imaging camera

Despite very rapid development of science in the recent years, the phenomena occurring in the electric arc have not been fully recognized. The main reason for this situation is their the complexity as well as very high temperatures. This paper presents the results of numerical calculations of phenomena which occur in the welding arc. The CFD Fluent package was used for modelling the following phenomena in the electric arc: melting, solidifying, generation of heat and multiphase flows. The 3D Model of a 50 × 30 × 6 mm metal plate segment padded with the use of the MIG method with a wire of 1.2 mm in diameter was developed. The paper focuses on presenting the distribution of temperatures in time, the process of melting and later solidifying of the material, as well as on the transport of the material from the arc to the padding weld. It also shows the initial verification of the model by comparing the results with a picture recorded by thermovisual camera.

Dry heat loses of newborn baby in infant care bed: use of a thermal manikin

The energy balance and heat exchange for newborn baby in infant care bed environment (radiant warmer) are considered. The present study was performed to assess the body dry heat loss from an infant in radiant warmer, using copper cast anthropomorphic thermal manikin and controlled climate chamber laboratory setup. The total body dry heat losses were measured for varying manikin surface temperatures (nine levels between 32.5oC and 40.1oC) and ambient air temperatures (five levels between 23.5oC and 29.7oC). Radiant heat losses were estimated based on measured climate chamber wall temperatures. After subtracting radiant part, resulting convective heat loses are compared with computed ones, based on Nu correlations for common geometries. Simplified geometry of newborn baby was represented as: (a) single cylinder and (b) weighted sum of 5 cylinders and sphere. The computed values are significantly overestimated relative to measured ones by: 28.8% (23.5%) for (a) and 40.9% (25.2%) for (b). This shows that use of adopted general purpose correlations for approximation of convective heat losses of newborn baby can lead to substantial errors, hence approximation formula is proposed. The thermal manikin appears to provide a precise method for the noninvasive assessment of thermal conditions in neonatal care.

Temperature-velocity coupling of the convective heat transfer sensitivity analysis

ABSTRACT This article deals with sensitivity studies of the temperature–velocity coupling of convective heat transfer problems with laminar fluid flow. Sensitivity coefficients contain information about the chances of a successful inverse procedure, and they can be used in a number of inverse schemes, i.e., the Levenberg-Marquardt method. Special emphasis is given in this article to the numerical solution of the direct problem, which was obtained by the control-volume finite-element method formulation. This numerical tool was used for the sensitivity coefficients evaluation and can be used for simulation of real measurements in the full inverse algorithm. The algorithm for the sensitivity coefficients evaluation and example distributions of the sensitivity coefficients are given. A proposed full inverse procedure, allowing determination of inflow velocity based on internal temperature measurements, is also included. The inverse method employs the Levenberg-Marquardt method for stabilization purposes.