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RISS 인기검색어
- 검색키워드
- 저자 : Bartzanas, T. (검색결과 3 건)
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Modelling of ammonia emissions from naturally ventilated livestock buildings. Part 3: CFD modelling
Bjerg, B.,Cascone, G.,Lee, I.B.,Bartzanas, T.,Norton, T.,Hong, S.W.,Seo, I.H.,Banhazi, T.,Liberati, P.,Marucci, A.,Zhang, G. Academic Press 2013 Biosystems engineering Vol.116 No.3
The purpose of this review paper is to identify current capabilities of Computational Fluid Dynamics (CFD) modelling techniques and areas where further scientific research is required, in order to identify how best CFD can be utilised in the future as a comprehensive modelling tool that enables naturally ventilated (NV) livestock buildings to be designed to reduce ammonia emissions. The review indicates that CFD methods possess many of the elements needed to develop reliable models for prediction of ammonia emission (AE) from NV livestock buildings. Nevertheless, development and validation of methods to specify boundary conditions regarding the ammonia-emitting surface is still a challenging task. In addition further development and validation is needed of (1) methods to model the influence of the animals and the influence of varying weather conditions, (2) strategies on how to select the most appropriate turbulence model relative to the modelling application at hand and computational power available, (3) more advanced solar irradiation models to gain more understanding of its effect on AE, (4) standardised sensitivity analysis of the uncertainties involved in the CFD model, (5) standard approaches to the incorporation of contaminant transfer across boundary layers of emitting surfaces within large scale simulations, and (6) more effective meshing techniques.
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Bjerg, B.,Norton, T.,Banhazi, T.,Zhang, G.,Bartzanas, T.,Liberati, P.,Cascone, G.,Lee, I.B.,Marucci, A. Academic Press 2013 Biosystems engineering Vol.116 No.3
Gaseous emissions from livestock buildings are a major environmental concern worldwide and an increasing number of countries have now introduced legislation that aims to reduce the emission of pollutants like ammonia. This paper is the first of a series of three reviews focussing on the utilisation of different modelling techniques to estimate ammonia emissions from naturally ventilated livestock buildings. Well-designed naturally ventilated buildings can provide occupants with good indoor air quality as well as energy consumption below levels for mechanically ventilated systems. But the time-dependence and the large fluctuations of air movement through the ventilation openings provide significant challenges for both modelling and measuring ammonia emission from naturally ventilated livestock buildings. This paper considers 12 studies published within the last 32 years that have included process-level models using mechanistic approaches for estimating ammonia release from different surfaces in cattle, pig and poultry buildings. Several models are available for predicting the release of ammonia from urine puddles on floors and from manure pits under pig and cattle buildings. Five models have been validated against measurements in mechanically or naturally ventilated livestock buildings with animals. One model predicted ammonia release from broiler litter, but it was based on laboratory measurements only. No mechanistic models were identified predicting ammonia release from mixtures of urine, faecal and bedding material on floor surfaces in pig and cattle buildings. Air velocity above the release surfaces was an important parameter in all the models. The models that were validated against full scale emission measurements used empirically determined relationships to estimate air velocity. CFD (Computational Fluid Dynamics) methods can provide a significant opportunity to model spatially and temporal distributed environmental conditions around ammonia release surfaces in livestock buildings. However, the full potential of integration of CFD with process level models of ammonia release cannot currently be realised because of the lack of good validation data and of the processing capacity needed to handle the complex computational needs of 3D CFD models.
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The past, present and future of CFD for agro-environmental applications
Lee, I.B.,Bitog, J.P.P.,Hong, S.W.,Seo, I.H.,Kwon, K.S.,Bartzanas, T.,Kacira, M. Elsevier 2013 Computers and electronics in agriculture Vol.93 No.-
Computational fluid dynamics (CFD) is a proven simulation tool which caters to almost any field of study. The CFD technique is utilized to simulate, analyze, and optimize various engineering designs. In this review, the discussion is focused on the application of CFD in the external atmospheric processes as well as modeling in land and water management. With respect to its application in environmental investigations, numerous CFD studies have been done in the atmospheric processes where generally only the fluid flow characteristics are investigated. The application of CFD to soil and water management is still limited. However, with the present demand for conservation and sustainable management of our soil and water resources, CFD application in this field is fast emerging especially in structure designs of dams and reservoirs where CFD offers fast reliable results with less labor and cost. Every CFD model should be validated in order to be considered accurate and reliable. However, a benchmark or standard procedures in validating CFD models is not yet available. This probably answers why the success of the CFD models is still mostly attributed to the user's skills and experience. At present, the degree of application of CFD to the agro-environmental field is limited by the computing power and software used, however, the fast ever computing power of PCs continually expands the potential of CFD and can be generally more flexible at accounting for the unique aspects of every CFD project. This allows easy access to conduct simulation studies from simple to complex models. In this paper, after a state of art analysis of the past and present application of CFD in the agro-environmental applications, its future directions were discussed, in order to potentially serve as a guide for researchers and engineers on what project or investigations can be conducted.
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