[Klaus M.]

I am newbie in CFD.

At general recommendation, hardware is so powerfull.
Why is that, is this recommendation for professionals use or amateurs?

If I doing just basics things like, wings , sails, can I do CFD on 1000€ laptop?

Please, can someone explain this.

[flotus1]

There is no minimum required level of hardware to do some CFD.
The amount of money spent -or more precisely- the type of hardware you buy, determines two things:

• the problem size you can tackle, mostly number of cells
• the time it takes to get a reasonable result

If all you want to do is some simple tutorials, or learn the basic use of any CFD-related software package, you can do that with pretty much any moderately modern PC/Laptop. I would still recommend 16GB of RAM and an SSD as the bare minimum to avoid frustration.
Once the cell count gets larger, and you want answers as quickly as possible, you will need some better equipment. Or take your workloads to some HPC cluster.

[Klaus M.]

Originally Posted by flotus1

There is no minimum required level of hardware to do some CFD.
The amount of money spent -or more precisely- the type of hardware you buy, determines two things:

• the problem size you can tackle, mostly number of cells
• the time it takes to get a reasonable result

If all you want to do is some simple tutorials, or learn the basic use of any CFD-related software package, you can do that with pretty much any moderately modern PC/Laptop. I would still recommend 16GB of RAM and an SSD as the bare minimum to avoid frustration.
Once the cell count gets larger, and you want answers as quickly as possible, you will need some better equipment. Or take your workloads to some HPC cluster.

What determine numbers of cells, object size, object complexity, mesh density or I arbitrary?

[flotus1]

A lot of factors go into the equation of "how much computing power do I need"
URANS takes longer than RANS, LES takes longer than URANS and typically requires finer grids.
If you are doing simulations on a single part for internal aerodynamics, this will require fewer cells than simulating the external aerodynamics of e.g. a whole car.
As an experienced user, you will be able to generate meshes with lower cell count for results of similar quality.
Block-stuctured hexahedral meshes require less computational effort than polyhedral meshes, but also require more interactive effort from the user.
Modelling complex physics is more expensive than simulating standard single-phase flows.
The list goes on...

Not sure what you mean by " object size, object complexity"

[Klaus M.]

Originally Posted by flotus1

Not sure what you mean by " object size, object complexity"

Airplane is very smooth "simple" object and F1 car is very complex object.

example F1 front wing

[flotus1]

Yep, that's the kind of stuff I lumped into the last point of my incomplete list.
External vehicle aerodynamics is one of the more demanding areas, with cell counts typically 100M+. This would indeed require a high-end workstation, or more realistically a whole HPC cluster. Because no matter how patient you are, these simulations will not run on a laptop due to a lack of RAM.

I'm a bit unsure where this is going. You can learn how to do CFD with any modern PC. Tackling real-world problems with acceptable turn-around times might require more computing horsepower. Depending on what your real-world problems are, and what is an acceptable time for you.
What usually happens is this: the problem size and fidelity quickly grows towards the limit of what your current hardware can handle anyway

[Klaus M.]

Originally Posted by flotus1

What usually happens is this: the problem size and fidelity quickly grows towards the limit of what your current hardware can handle anyway

So that means, no sense to buy high expensive desktop workstation if even this would be to small.
So better stay with better laptop of 32GB RAM?

[flotus1]

Don't know what to tell you...
For the purposes outlined in the initial post, any modern laptop will do. Without knowing what other CFD problems you want to tackle, it is pretty much impossible to make any recommendations.

[Klaus M.]

Originally Posted by flotus1

Don't know what to tell you...
For the purposes outlined in the initial post, any modern laptop will do. Without knowing what other CFD problems you want to tackle, it is pretty much impossible to make any recommendations.

Ok thanks for help.

[flotus1]

Let me just run by a few random thoughts:
If you decide to go with a laptop, I would recommend getting one with at least 2 physical DIMM slots, not just a fixed amount soldered onto the motherboard. If need be, this will allow you to upgrade the memory. Memory is cheap, and the main limiting factor for the size of simulations you can run. It might take a long time if the CPU just isn't powerful enough, but it will get the job done eventually.
More generally speaking, that's one of the reasons why I tend towards desktop PCs if the circumstances allow it. They can easily be upgraded when the requirements increase. You can keep stuff like case, power supply, graphics card etc. and just swap motherboard, CPU and memory.