About the book: This book is intended for Undergraduate and First year Post graduate students in the disciplines of Mechanical and Aerospace engineering. Also, scientists and engineers working in the areas of aerospace propulsion and gas dynamics should find this book to be a valuable addition to their collection of books on the subject matter. The unique feature of the book is the emphasis on both the mathematical and physical aspects of compressible flows. The subject matter is presented in increasing order of complexity, starting from simple one dimensional flows through quasi one dimensional flows to oblique shocks and Prandtl Meyer flow. The treatment interleaves mathematical development of the concepts and physical insights. Worked examples and exercise problems have almost all been drawn from practical applications in propulsion and gas dynamics. These are comprehensive and are formulated to test the understanding of the subject matter and thus serve as a self-check for the reader.