Here are some of my views:

CFD involves a number of assumptions. Use of assumptions introduces a number of errors to your solutions. Hence, there is an uncertainty involved in CFD solutions. In order to ensure that these uncertainties are within acceptable values, validation has to be carried out experimentally or analytically. If CFD and experimental results are in good agreement with regards to numerical values or trends then you can consider that the your CFD model can serve as a powerful and an efficient tool for future investigations where experimental results are not available for a similar domain of interest where validation has already been done.

When validation is not done properly the solution or results you obtain from CFD may not always be reliable and decisions taken based on such solutions can lead to potential risks/dangers.

The other alternative to CFD is carrying out experiments but experiments can involve heavy risks/dangers specially in scenarios where high speed rotating equipment or dangerous chemicals are involved. In addition to the risks/dangers experiments still have uncertainties associated with measuring equipment and also the assumptions that are made in the experiment. Hence experimental results can still differ from the actual scenario that is being recreated in the lab. In these situations CFD can serve as a very promising and an powerful tool.

In a nutshell both CFD and experiments have their own advantages and drawbacks.

Here are some of my views:

CFD involves a number of assumptions. Use of assumptions introduces a number of errors to your solutions. Hence, there is an uncertainty involved in CFD solutions. In order to ensure that these uncertainties are within acceptable values, validation has to be carried out experimentally or analytically. If CFD and experimental results are in good agreement with regards to numerical values or trends then you can consider that the your CFD model can serve as a powerful and an efficient tool for future investigations where experimental results are not available for a similar domain of interest where validation has already been done.

When validation is not done properly the solution or results you obtain from CFD may not always be reliable and decisions taken based on such solutions can lead to potential risks/dangers.

The other alternative to CFD is carrying out experiments but experiments can involve heavy risks/dangers specially in scenarios where high speed rotating equipment or dangerous chemicals are involved. In addition to the risks/dangers experiments still have uncertainties associated with measuring equipment and also the assumptions that are made in the experiment. Hence experimental results can still differ from the actual scenario that is being recreated in the lab. In these situations CFD can serve as a very promising and an powerful tool.

In a nutshell both CFD and experiments have their own advantages and drawbacks.