The answer to the question is "Yes, it is possible to simulate arterial rain".
This question is very important in interpreting the evidence found at Harrowdown Hill.
Two possibilities exist for the cause of the supposed arterial rain found on the nettles to the left of the body:
- Arterial bleeding from the left wrist of the body
- Simulated arterial rain by the person I referred to as the "Scene Setter" here: The Death of David Kelly - The blood distribution indicates it was murder
It is not at all surprising that arterial rain can be simulated. After all, arterial bleeding is simply fluid being expelled from a tube under pulsatile pressure.
Not only is it possible to simulate arterial rain, it is so straightforward to do so that it is used in teaching forensic science.
One simulation technique is simply to use a syringe and tube. This is used at the Department of Forensic Science in Virginia. See Bloodstain Pattern Training Manual. Relevant material is in section 5.4.9 on page 19 of the PDF file.
The second simulation technique is to use a peristaltic pump (broadly a pump that produces pulses of pressure analogous to the pulses in the arteries, caused by pumping by the left ventricle of the heart). See Crime Scene to Court: The Essentials of Forensic Science - Google Books Result. The relevant section is Section 184.108.40.206 on page 179.
It is clear that simulation of arterial rain is sufficiently close in its characteristics to "genuine arterial rain" that the simulated arterial rain can be used for teaching purposes in the training of forensic science professionals.
Was Mr. Green aware that simulating arterial rain was straightforward?
If he was, he didn't disclose it to Lord Hutton in his oral evidence nor did he disclose that possibility in his report of 27th September 2003 (Roy Green forensic statement 27 September 2003).
Given that it is so straightforward to simulate arterial rain the safety of Mr. Green's conclusion the blood on the nettles arose from arterial bleeding from the left wrist of the body is obviously called into question.
I will be writing to the Attorney General's Office asking that an urgent expert review be carried out of Mr. Green's assessment of this aspect of the evidence at Harrowodown Hill