Does anybody know the references regarding the object-oriented programming in CFD especially programming with C++ and Java?

Try:

Weller, H.G.; Tabor G.; Jasak, H. and Fureby, C.: Tensorial Approach to CFD using Object Orientated Techniques, Computers in Physics, 1998 v 12 n 6, pp 620-631

Not specifically related to C++ but more generally, see

Scientific and Engineering C++, by Barton and Nackman

G. Buzzi-Ferrari: Scientific C++ (Addison-Wesley 1993)

Numerical Recipes iN C++.

Another source is the Diffpack package, described as "a set of libraries." It was originally developed in a university environment with a publicly distributed version, but the current version is proprietary and distributed by a company called Numerical Objects. Information can be found at www.nobjects.com. On request they will send you a CD with documentation and a lot of code for free. There are examples of application to some CFD problems. They will send you a key, valid for a month or so, which allows you to develop and use their libraries for your application. The key can be renewed, or you can buy a license. There is also a text "Computational Partial Differential Equations, Numerical Methods and Diffpack Programming," by H. P. Langtangen.

But the important thing for your purposes is that there is source code you can study and adapt for your own purposes. The catch is that the source for the numerical solvers is not included, but you can piece that together yourself.

I am using FOAM from www.nabla.co.uk and I am enjoying it very much. It is C++, open source.

I do not see a download link on their website. How did you get the routines?

Leo:

It is only free for academic use. Send them a request.