Title: An Illustrative Discussion of Equation of State Modelling Speaker: Igor V. Lomonosov, Institute of Problems of Chemical Physics, Chernogolovka, Russia Date/Time: Thursday, April 6, 2006, 10:00 – 11:00 am Location: Building 980, Room 95 (Sandia NM) Brief Abstract: I will present a multi-phase EOS model accounting for solid, liquid, gas and plasma states of aluminum, as well as two-phase regions of melting and evaporating. The available high pressure, high temperature data for aluminum include results of band-structure, quantum molecular dynamics and plasma theories, and static and dynamic, i.e. shock-wave, experiments. Beyond illustrating many of the steps to developing an EOS, I will address the long-standing question of whether aluminum undergoes a structural phase transformation above 200 GPa on the principal Hugoniot. The analysis deals with thermodynamic properties of solid Al at T=0 and 298 K from different band-structure theories and static compression experiments. Information obtained in isentropic-compression and shock-wave experiments will be also discussed. Thermodynamic data in liquid state resulting from traditional thermophysical measurements, “exploding wires” experiment, evaluations of the critical point and QMD calculations will be presented. Numerous shock-wave experiments for Al have been done to measure shock adiabats of crystal and porous samples, release isentropes and sound speed in shocked metal. These data will be analyzed in a self-consistent manner together with all other available data at high pressure. The model’s results will be shown for the principal shock adiabat, positions of high-pressure melting and evaporating regions and parameters of the critical point of aluminum. Typical features and possibilities of developed EOS will be discussed along with the problem of EOS incorporating in gas dynamic codes. Methods of use of this multi-phase EOS in tabular form in numerical modeling will be also presented. The importance of correct description of phase boundaries will be demonstrated for the case of hypervelocity impact.CSRI POC: John Aidun, (505) 844-1209 |