UDS means that User Defined Scalars where you can solve extra equation which conatins all terms like unsteady, convective, diffusive and source terms.

Is it possible to connect this UDS equation with other equations this connection could be two way.

1) I mean for example source terms can be function of velocity or pressure.

2) But I let us say that k or epsilon or density is the functions of scalar (which you are solving in UDS).

I am new in UDS I would like to know whther somebosy modelled such a system where both connections are present.

1) Yes, source terms can be a function of whatever flow variable you need.

2) What do you mean? You can, for example, define a boundary condition for k or epsilon as a function of your UDS. In this sense, it's possible. You have to write a UDF for that.

Best regards, ap