isentropischer

"Isentropischer" is the German adjectival form of "isentropic," used to describe processes or conditions in which entropy remains constant. In thermodynamics and fluid dynamics, an isentropic process is an idealization that combines adiabatic behavior (no heat transfer) with reversibility, so that the specific entropy s of the system does not change (ds = 0).

For an ideal (perfect) gas undergoing an isentropic process, common relations simplify analysis: p v^γ = constant, p / ρ^γ = constant, and T v^(γ−1) = constant, where p is pressure, v specific volume, ρ density, T temperature, and γ = c_p / c_v is the ratio of specific heats. These relations lead to practical formulas such as T2/T1 = (p2/p1)^((γ−1)/γ). Isentropic flow assumptions underpin many aerodynamic and turbomachinery calculations, including nozzle design, compressor and turbine performance, and shock-free flow approximations.

As an idealization, isentropic behavior is rarely exact in real systems because of viscous dissipation, heat transfer, and other irreversible effects. Engineers therefore use the isentropic model as a reference state and define isentropic efficiency to quantify deviation from the ideal. Linguistically, "isentropischer" appears in German technical writing as an attributive adjective (for example, isentropischer Prozess — isentropic process).