Modeling is done by using GT-POWER [15]. Gas dynamic
models have been introduced a very long time ago for
description of engine flow and combustion. Pioneering codes
based on the method of characteristics were used in the
sixties on the very poor computer hardware of the time [16].
Since end of the eighties and beginning of the nineties
a number of well developed numerical codes based on the
finite difference methods have been made available in the
market becoming increasingly popular for engine research
and development. GT-POWER is the industry-standard
engine simulation tool, used by most leading engine and
vehicle makers and their suppliers. Other very popular codes
these days are WAVE [17] and BOOST [18]. In view of the fact
that the computational approach used in GT-POWER is very
well known, only parts of specific interest here are discussed
in this section.