A Monte Carlo approach to radiative transfer in participating media is described and tested. It solves to a large extent the well known problem of Monte Carlo simulation of optically thick absorption conÿgurations. The approach which is based on a net-exchange formulation and on adapted optical path sampling procedures is carefully designed to insure satisfactory convergence for all types of optical thicknesses. The need for such adapted algorithms is mainly related to the problem of gaseous line spectra representation in which extremely large ranges of optical thicknesses may be simultaneously encountered. The algorithm is tested against various band average computations for simple geometries using the Malkmus statistical narrow band model. ?

It is shown that, starting from any existing Monte Carlo algorithm for estimation of a physical quantity A, it is possible to implement a simple additional procedure that simultaneously estimates the sensitivity of A to any problem parameter. The corresponding supplementary cost is very low as no additional random sampling is required. The principle is presented on a formal basis and simple radiative transfer examples are used for illustration.

No abstract

No abstract

No abstract

In several applications such as meteorology or combustion, it is difficult to consider detailed radiative transfer modeling because of the high computing cost due to the numerous coupled physical phenomena such as fluid mechanics, heat transfer and chemistry. The aim of this work is to present an attempt to couple a highly accurate radiative transfer model to an advanced combustion code. This approach is based on a recently identified specific feature of Monte Carlo Methods. They provide not only the radiative source field but also its sensitivities to temperatures and concentrations with no additional random procedure. To illustrate this approach, a coupled simulation applied to a 1-D counterflow flame is presented.