Analysis differences with respect to size
 

I have a wooden computer. So solving big geometries is nearly impossible. When I scale geometry like 1/10 would that matter or change the results ?

It depends on what you are doing, but scaling the size is not a smart solution.
Geometric Size should not matter for calculation time. It is the # of mesh elements which matters.

Yes the problem starts after meshing. I have a wooden pc and if my mesh number goes like 2m computer gives me headaches. Solution takes hours and i cant even see if its right or wrong. So I thought i could scale body, give appropriate meshing and solve it in a hour. But it is not ideal, you say.

Scaling can be done, provided the Re number is the same. Therefore the computational resolution, required for your case is the same even after scaling.

Several hours of computational time are quite normal...

So if i rearrenge re number an continue with scaled geometry it is ok. I am trying to solve for a small aircraft. But geometry is too big for pc. Always stops, program freezes etc.

To re-iterate what FMDenaro wrote: scaling the geometry does not achieve anything with regards to computational cost.
If you decreased the geometric size of your model by a factor of 10, you would need to e.g. decrease viscosity by a factor of 10 in order to have the same Reynolds Number. Otherwise, you would change physics, and get absolutely useless results in regards to your original case.
That in turn means your cell size would also have to decrease by a factor of 10 in order to achieve the same resolution.
You can scale the geometric size all you want, it does nothing to reduce computational cost.