Generalised Isentropic Relations in Thermodynamics

Isentropic processes in thermodynamics are fundamental to our understanding of numerous physical phenomena across different scientific and engineering fields. They provide a theoretical reference case for the evaluation of real thermodynamic processes and observations. Yet, as analytical relations for isentropic transformations in gas dynamics...

Preliminary Experiments in High Temperature Vapours of Organic Fluids in the Asymmetric Shock Tube for Experiments on Rarefaction Waves (ASTER)

This paper describes the design, functioning, and preliminary experiments in the Asymmetric Shock Tube for Experiments on Rarefaction Waves (ASTER), a Ludwieg-type shock tube designed and realised to measure waves propagating in dense vapour flows of organic fluids. The setup is designed to operate at pressures and temperatures of up to 15...

Determination of the Ideal Gas Isobaric Heat Capacity of D4 using experimental speed of sound measurements

The research presented regards the study of D4 using experimental speed of sound measurements to obtain the ideal gas isobaric heat capacity. The isobaric heat capacity is not a useful property for the generation of equations of state, in the presented research it is used for the validation of thermodynamic models. However, due to the observed...

Ultrasonic Propagation in Planetary and Interstellar Ices: An experimental approach

Comets are celestial objects that are thought to have formed at the outer edges of our solar system. The ices they contain is thought to be preserved since their formation in the molecular cloud phase, before the formation of the sun. The formation of ices in the molecular cloud occur via the ice mantle accretion rocess, by condensation of...

On using variable molecular masses in multicomponent lattice Boltzmann simulations

The option of varying the molecular mass in multicomponent lattice Boltzmann simulations is being explored. First, results are presented for droplet formation at an aperture in a second immiscible liquid medium in which the difference in density between the two media is achieved by introducing asymmetry in the EOS, via adding particularly...

A Novel Acoustic Resonator for Speed of Sound Measurement in Dense Organic Vapours

Speed of sound measurements are currently of the utmost importance for the development of thermodynamic models of fluids. A need for accurate thermodynamic models was identified for siloxanes, because of their use as working fluid in organic Rankine cycle power systems and because of the scientific interest in non ideal and non classical gas...

Ultrasound imaging of the brain using full-waveform inversion

Transcranial ultrasound has been used to image the brain since 1942. Currently, it is regaining interest and full-waveform inversion (FWI) methods are now employed to reconstruct speed-of-sound profiles of the brain. Many of these methods require a good starting model. Here, we test the applicability of contrast source inversion (CSI) as a...

Real Gas Thermodynamics: and the isentropic behavior of substances

A generalized isentropic gas model is derived following earlier work by Kouremenos et al. in the 1980s, by replacing the traditional adiabatic exponent γ by the real exponents γPv, γTv, and γPT, describing the isentropic pressure-volume, temperature-volume, and pressure-temperature relations respectively. The real adiabatic exponents are...

Preconditioning applied to Eulerian-Eulerian gas-solid flow calculations with variable gas density

Local preconditioning for Eulerian-Eulerian gas-solid flow calculations with variable gas density is investigated. The performance of simultaneous solution algorithms for low-Mach calculations is strongly related to preconditioning. The gas-solid drag source terms are at the origin of a solid volume fraction and frequency dependency of the...