Reduced finite-volume model for the fast numerical calculation of the fluid flow in the melt pool in laser beam welding

In this paper we propose a reduced two-dimensional finite-volume model for the fast calculation of the melt flow. This model was used to determine the influence of the welding speed, viscosity in the melt and vapour flow inside of the keyhole on the fluid flow field, the temperature distribution, and the resulting weld-pool geometry for laser beam welding of aluminium. The reduced computational time resulting from this approach allows the fast qualitative investigation of different aspects of the melt flow over a wide range of parameters. It was found that the effect of viscosity within the melt is more pronounced for lower welding speeds whereas the effect of friction at the keyhole walls is more pronounced for higher welding speeds. The weld-pool geometry mainly depends on the welding speed.

Microstructural Prediction of Heat Treated Steel Forgings for Severe Applications

An in-house 2D finite volume model, specific for components of simple shape, was developed and applied to predict the thermal and microstructural evolution during heat treatment of steel forgings. The results of the thermal metallurgical modelling, including hardness profiles through the thickness, were compared with the experimental ones. Moreover, the 3D FEM software Deform-HT, able to calculate the thermal and microstructural evolution and the stress field during quenching, was specialized for the cases of interest. Examples of optimal heat treatment to develop the target microstructure and strength and reduce the risk of quenching cracks are discussed.

Baseflow and flash flood models of the ungaged Morgó watershed

<p><strong>Baseflow and flash flood models of the ungaged Morgó watershed</strong></p><p><strong>Gergely Amon<sup>1</sup> and Katalin Bene<sup>2</sup></strong></p><p><strong><sup>1</sup>Department of Transport Infrastructure and Water Resources Engineering, Széchenyi István University, Győr, Hungary, [email protected] </strong></p><p><strong><sup>2</sup>Department of Transport Infrastructure and Water Resources Engineering, Széchenyi István University, Győr, Hungary, </strong><strong>[email protected]</strong></p><p> </p><p>Abstract: A common feature of steep-sloping watersheds is that there is a significant difference between base flow and flash floods; sometimes two or three orders of magnitude. In Hungary, these streams are usually ungaged or the available flow data is very limited. The Morgó creek watershed, located in northern part of Hungary, features steep terrain, and both urban and natural land use conditions.</p><p>In this paper, different models are applied to evaluate flash floods, and baseflow conditions in the Morgó-creek watershed. High probability baseflows can help to evaluate and monitor the current and future condition and health of the local ecological systems. Modeling flash floods with low probability can help to assess and prevent damage in urban areas.</p><p>Different types of models are required to generate baseflow and flash flood scenarios. For baseflow modelling, a two-dimensional finite element method was used while for flash floods, a finite volume model was applied. Morgó creek has a high peak flow, with a sharply increasing rising limb. As a result, the finite volume model is not sensitive to mesh density. Additionally, the impact of roughness coefficient was less than expected during calibration. The low flow analysis requires a more complex model to account for turbulence; therefore, the Shallow Water equations were used in the finite element model.</p><p>Uncertainty in hydrological model parametrization are a source of significant prediction errors. Monte Carlo simulation was applied to quantify parameter uncertainty on watershed response. The analysis was then used in the hydrodynamic model to assess the final prediction error for baseflow and flash flood conditions. While the hydrodynamic baseflow and flash flood models have different space and time scales, the two model solutions do influence each other. Proper analysis and comparison of the selected scenarios can help to determine an optimal design for the Morgó-creek watershed.</p><p>This work was undertaken as part of a project funded by the EFOP-3.6.1-16-2016-00017.</p>

Numerical Simulation of Flood Inundation in a Small-Scale Coastal Urban Area Due to Intense Rainfall and Poor Inner Drainage

: This study presents the numerical simulation and analysis of the characteristics of the flood inundation in a small-scale coastal urban area due to the intense rainfall and poor inner drainage from the tidal level rise occurring during a typhoon. The employed numerical model is a two-dimensional finite volume model with a well-balanced HLLC (Harten–Lax–Van Leer contact) scheme. The target area is a coastal urban area downstream of the Gohyun river; which is located in Geoje City of Kyungsangnam Province, Korea. This area was significantly damaged by flood inundation due to the heavy rainfall and significant increase in the tidal level during Typhoon “Maemi”, which occurred in September 2003. The numerical model used in this study is verified using the flood inundation traces observed in the selected urban area. Moreover; the characteristics of the flood inundation based on the change in the river inflow due to the increase or decrease in the intensity of the possible heavy rainfall that may occur in the future are simulated and analyzed.