Computational Fluid Dynamics a branch of engineering that can be categorized under Aerospace Engineering. It involves simulation of fluid flows. Fluid dynamics is a branch of physics that governs the equations of fluid motion. This equations can be solved numerically using computers and that is precisely what a CFD engineer does. A CFD simulation can be used to in designing an aircraft, blood flow in a abnormal artery, the combustion efficiency of a rocket engine, the heat transfer rates in complex heat exchangers, optimising the performance of wind turbines and estimating the potential scale of floods.

Expatriate taxation deals with the direct tax (virtually income tax and wealth tax) of expatriates.
An expatriate (commonly abbreviated expat) is a person temporarily or permanently residing in a country and culture other than that of the person's upbringing. During the latter half of the 20th century, expatriation was dominated by professionals sent by their employers to foreign subsidiaries or headquarters.
Since the globalization has given rise to increase in number of expatriates throughout the world, it has become important for employers to concentrate on high transfer costs, the possibility of encountering local government restrictions and encountering tax costs.
Taxation is one of the aspects that employers need to pay special attention to reduce the tax costs as well as to be tax compliant. Generally these employers are multinational organizations; hence they prefer availing these services from multinational or global taxation services providers (like Big 4s) who have their counterparts in the major exposed countries.