Modelling of a Wall Inlet in Numerical Simulation of Airflow in Livestock Buildings

Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a Technical Article from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 4 (2002): B. Bjerg, K. Svidt, S. Morsing, G. Zhang, and J.O. Johnson. Modelling of a Wall Inlet in Numerical Simulation of Airflow in Livestock Buildings. Vol. IV. March 2002

Modeling of air inlets in CFD prediction of airflow in ventilated animal houses

Abstract This study investigates different methods to model wall inlets in computational fluid dynamics (CFD) simulations of airflow in livestock rooms. The experiments were carried out in an 8.5 m long, 3 m high and 10.14 m wide test room equipped with a forced ventilation system. Four wall inlets were distributed symmetrically along an end wall 0.5 m beneath the ceiling. To obtain uniform and easily modeled boundary conditions the inlets were designed as rectangular frames with an elliptic profile in the contraction section following the ISO standard for a long-radius nozzle. Vertical and horizontal air speed profiles in the jets were measured with thermistor speed sensors at four distances from the inlets and an ultrasonic sensor was used for measurement of air velocity in the occupied zone close to the floor. CFD-simulations with the k-o turbulence model were carried out with a number of different grid constructions. Both measurement and CFD simulations showed that two different airflow patterns occurred in the test room. In airflow pattern 1 the jets beneath the ceiling turned towards the symmetry plane of the room and above the floor the air flowed away from the symmetry plane. In air flow pattern 2 the jets turned away from the symmetry plane and above the floor the air flowed towards the symmetry plane. The findings in this study indicate that assuming two dimensional (2-D) inlet conditions might be a useful way to simplify inlet boundary conditions and grid constructions for prediction of air flow in the occupied zone of livestock rooms with many wall inlets. However, more work must be done to evaluate this statement in other arrangements, including changed orientation and loca

Iron Oxide Nanoparticles as a Contrast Agent for Synchrotron Imaging of Sperm

Fast phase-contrast imaging offered by modern synchrotron facilities opens the possibility of imaging dynamic processes of biological material such as cells. Cells are mainly composed of carbon and hydrogen, which have low X-ray attenuation, making cell studies with X-ray tomography challenging. At specific low energies, cells provide contrast, but cryo-conditions are required to protect the sample from radiation damage. Thus, non-toxic labelling methods are needed to prepare living cells for X-ray tomography at higher energies. We propose using iron oxide nanoparticles due to their proven compatibility in other biomedical applications. We show how to synthesize and attach iron oxide nanoparticles and demonstrate that cell-penetrating peptides facilitate iron oxide nanoparticle uptake into sperm cells. We show results from the TOMCAT Nanoscope (Swiss Light Source), showing that iron oxide nanoparticles allow the heads and midpiece of fixed sperm samples to be reconstructed from X-ray projections taken at 10 keV.Comment: 21 pages, 6 figure

Seasonal variations of Saanen goat milk composition and the impact of climatic conditions

The aim of this research was to investigate the effect of climatic conditions and their impact on seasonal variations of physico-chemical characteristics of Saanen goat milk produced over a period of 4 years. Lactation period (early, mid and late) and year were considered as factors that influence physico-chemical composition of milk. Pearson's coefficient of correlation was calculated between the physico-chemical characteristics of milk (fat, proteins, lactose, non-fat dry matter, density, freezing point, pH, titrable acidity) and climatic condition parameters (air temperature, temperature humidity index-THI, solar radiation duration, relative humidity). Results showed that all physico-chemical characteristics of Saanen goat milk varied significantly throughout the lactation period and years. The decrease of fat, protein, non-fat dry matter and lactose content in goat milk during the mid-lactation period was more pronounced than was previously reported in the literature. The highest values for these characteristics were recorded in the late lactation period. Observed variations were explained by negative correlation between THI and the physico-chemical characteristics of Saanen goat milk. This indicated that Saanen goats were very prone to heat stress, which implied the decrease of physico-chemical characteristics during hot summers