Chung K. Law

Bio: Chung K. Law is an academic researcher from Princeton University. The author has contributed to research in topics: Combustion & Premixed flame. The author has an hindex of 95, co-authored 640 publications receiving 32945 citations. Previous affiliations of Chung K. Law include General Motors & University of California, San Diego.

A directed relation graph method for mechanism reduction

Abstract: A systematic approach for mechanism reduction was developed and demonstrated. The approach consists of the generation of skeletal mechanisms from detailed mechanism using directed relation graph with specified accuracy requirement, and the subsequent generation of reduced mechanisms from the skeletal mechanisms using computational singular perturbation based on the assumption of quasi-steady-state species. Both stages of generation are guided by the performance of PSR for high-temperature chemistry and auto-ignition delay for low- to moderately high-temperature chemistry. The demonstration was performed for a detailed ethylene oxidation mechanism consisting of 70 species and 463 elementary reactions, resulting in a specific skeletal mechanism consisting of 33 species and 205 elementary reactions, and a specific reduced mechanism consisting of 20 species and 16 global reactions. Calculations for laminar flame speeds and nonpremixed counterflow ignition using either the skeletal mechanism or the reduced mechanism show very close agreement with those obtained by using the detailed mechanism over wide parametric ranges of pressure, temperature, and equivalence ratio.

Regimes of coalescence and separation in droplet collision

Abstract: An experimental investigation of the binary droplet collision dynamics was conducted, with emphasis on the transition between different collision outcomes. A series of time-resolved photographic images which map all the collision regimes in terms of the collision Weber number and the impact parameter were used to identify the controlling factors for different outcomes. The effects of liquid and gas properties were studied by conducting experiments with both water and hydrocarbon droplets in environments of different gases (air, nitrogen, helium and ethylene) and pressures, the latter ranging from 0.6 to 12 atm. It is shown that, by varying the density of the gas through its pressure and molecular weight, water and hydrocarbon droplets both exhibit five distinct regimes of collision outcomes, namely (I) coalescence after minor deformation, (II) bouncing, (III) coalescence after substantial deformation, (IV) coalescence followed by separation for near head-on collisions, and (V) coalescence followed by separation for off-centre collisions. The present result therefore extends and unifies previous experimental observations, obtained at one atmosphere air, that regimes II and II do not exist for water droplets. Furthermore, it was found that coalescence of the hydrocarbon droplets is promoted in the presence of gaseous hydrocarbons in the environment, suggesting that coalescence is facilitated when the environment contains vapour of the liquid mass. Collision at high-impact inertia was also studied, and the mechanisms for separation of the coalescence are discussed based on time-resolved collision images. A coalescence/separation criterion defining the transition between regimes III and IV for the head-on collisions was derived and found to agree well with the experimental data.

Boundary Layer Theory

Abstract: The boundary layer equations for plane, incompressible, and steady flow are $$\matrix{ {u{{\partial u} \over {\partial x}} + v{{\partial u} \over {\partial y}} = - {1 \over \varrho }{{\partial p} \over {\partial x}} + v{{{\partial ^2}u} \over {\partial {y^2}}},} \cr {0 = {{\partial p} \over {\partial y}},} \cr {{{\partial u} \over {\partial x}} + {{\partial v} \over {\partial y}} = 0.} \cr }$$

Handbook of Chemistry and Physics

Abstract: There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate