Journal of Samara State Technical University, Ser. Physical and Mathematical SciencesJournal of Samara State Technical University, Ser. Physical and Mathematical Sciences1991-86152310-7081Samara State Technical University10677110.14498/vsgtu1922Research ArticleThe characteristic Cauchy problem of standard form for describing the outflow of a polytropic gas into vacuum from an obligue wallPon’kinEugeny I.<p>Postgraduate Student</p>epnk@rambler.ruhttps://orcid.org/0000-0002-7848-3167Snezhinsk Physic Institute of the National Research Nuclear University MEPhI300620222623223382604202229062022Copyright © 2022, Authors; Samara State Technical University (Compilation, Design, and Layout)2022<p>The initial-boundary value problem for the system of equations of gas dynamics, the solution of which describes the expansion of a polytropic gas into vacuum from an oblique wall in the space of self-similar variables<span id="MathJax-Element-1-Frame" class="MathJax" tabindex="0"></span><span id="MathJax-Span-1" class="math"><span id="MathJax-Span-2" class="mrow"><em><span id="MathJax-Span-3" class="mi">x</span></em><span id="MathJax-Span-4" class="texatom"><span id="MathJax-Span-5" class="mrow"><span id="MathJax-Span-6" class="mo">/</span></span></span><em><span id="MathJax-Span-7" class="mi">t</span></em></span></span>,<span id="MathJax-Element-2-Frame" class="MathJax" tabindex="0"></span><span id="MathJax-Span-8" class="math"><span id="MathJax-Span-9" class="mrow"><em><span id="MathJax-Span-10" class="mi">y</span></em><span id="MathJax-Span-11" class="texatom"><span id="MathJax-Span-12" class="mrow"><span id="MathJax-Span-13" class="mo">/</span></span></span><em><span id="MathJax-Span-14" class="mi">t</span></em></span></span>in the general inconsistent case, is reduced to the characteristic Cauchy problem of standard form in the space of new independent variables<span id="MathJax-Element-3-Frame" class="MathJax" tabindex="0"></span><span id="MathJax-Span-15" class="math"><span id="MathJax-Span-16" class="mrow"><span id="MathJax-Span-17" class="mi"></span></span></span>,<span id="MathJax-Element-4-Frame" class="MathJax" tabindex="0"></span><span id="MathJax-Span-18" class="math"><span id="MathJax-Span-19" class="mrow"><span id="MathJax-Span-20" class="mi"></span></span></span>. Equation<span id="MathJax-Element-5-Frame" class="MathJax" tabindex="0"></span><span id="MathJax-Span-21" class="math"><span id="MathJax-Span-22" class="mrow"><span id="MathJax-Span-23" class="mi"></span><span id="MathJax-Span-24" class="mo">=</span><span id="MathJax-Span-25" class="mn">0</span></span></span>defines the characteristic surface through which the double wave adjoins the well-known solution known as the centered Riemann wave. Equation<span id="MathJax-Element-6-Frame" class="MathJax" tabindex="0"></span><span id="MathJax-Span-26" class="math"><span id="MathJax-Span-27" class="mrow"><span id="MathJax-Span-28" class="mi"></span><span id="MathJax-Span-29" class="mo">=</span><span id="MathJax-Span-30" class="mn">0</span></span></span> means that an oblique wall is chosen for the new coordinate axis, on which the impermeability condition is satisfied. For this new initial-boundary value problem, in contrast to the well-known solution of a similar problem obtained by S.P.Bautin and S.L.Deryabin in the space of special variables, the theorem of existence and uniqueness for the solution of the system of equations of gas dynamics in the space of physical self-similar variables in the form of a convergent infinite series was proved. An algorithm is described to build the series coefficients.</p>characteristic Cauchy problem of standard formanalogue of Kovalevskaya's theoremcharacteristic surfaceoblique wallseries coefficient construction algorithmхарактеристическая задача Коши стандартного видааналог теоремы Ковалевскойхарактеристическая поверхностькосая стенкаалгоритм построения коэффициентов ряда[Courant R., Hilbert D. Methods of Mathematical Physics, vol. 2, Partial Differential Equations. New York, London, John Wiley & Sons, 1962, xxii+830 pp.][Stanyukovich K. P. Unsteady motion of Continuous Media. 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