Are you trying to capture the flow around every single fin? That's not really a smart way to go about it if you'll excuse me saying so.
I would start by modeling a short section, with detailed fins. You can use this to find your convective heat transfer coefficient. After that you could model your radiator pipes, although I really don't see why you would need CFD for that. You should be able to figure out the pressure losses and flow rate from a simple 1-D flow network analysis, there's lots of data out there for circular pipe flows.
Thank you for your answer amit.
I have defined the : inlet and outlet of the Water flow at a special Temperature, the fluidvolume and some other parameters,Im writing on a thesis and the subject is: construction and design of a weight reduced cooling system for a formula car.
the calculation of the needed cooler is finished, and i designed the radiator...now i want to show how the aluminium radiator heats up when the hot water flows through the radiator, and later i want to do another flow simulation (airflow ) of the fan + cooling effect of the fan (impact of the radiator). But now i recognize that this assembly is maybe to big to simulate (takes to much time)
So you mean its enough when i just took just took the fin and fox example 2 tubes from the Radiator Core and do it with this? (like in the link below?
Is it possible to simulate air flow past a section of a car radiator with fluid flowing through it at the same time?
and where can i get some 1 -D flow network analysis software, i never heard about it, and are these freeware?
you have to know im new in this area of simulation :S thanks for reply .
You need to consider the order of magnitude. In order to get good data from flow simulation, you need to have a certain amount of cells across the smallest diameter or channel width. Additionally since there is no 2D simplification of plate or thin parts, you also need a certain amount of cells inside the thinnest section of solid material that is conducting heat. This presents a limit on how much detail you can include in the simulation.
This is why I suggested doing a "zoomed in" detailed analysis of the pipe and a few fins, to get a generalized convective heat transfer coefficient for your designed geometry.
As for the 1-D flow network analysis, there is software such as MacroFlow, but it's not free. But that shouldn't prevent you from doing some old fashioned pen and paper math. After all, that's why you had to sit through all those fluid dynamics lectures. There's plenty of literature out there about common pipe fittings and bends that will help you formulate the head loss, and you can use the convective heat transfer coefficient from the simulation to solve the energy balance.