Density greyscale of an axisymmetric simulation (top half only shown) of a propagating jet (M=10, η=0.1) from left to right with: (top) passive magnetic field; (middle) strong toroidal field (β=0.2); and (bottom) strong poloidal field (β=0.2) all after the same propagation time. In 2-D, a toroidal field enhances propagation speed, a poloidal field impedes it.

 

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The maiden AZEuS simulation showing the Alfvénic Mach number (colours) and magnetic field lines of a protostellar jet with eight levels of refinement. This is the first simulation to follow a magnetocentrifugally launched jet (at resolution 0.00625 AU) to observational scales (2,000 AU) where the jet takes on its familiar bow-shock led morphology. See Ramsey & Clarke for details.

 

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Line-of-sight integration of the pseudo-synchrotron emission of two ZEUS-3D simulations of supersonic (M=10), light (η=0.1) jets with: (top) a trace magnetic field; and (bottom) a strong (β=0.2) toroidal magnetic field. Jet propagation is from left to right.

 

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Line-of-sight integration of  ∇ · v  in a jet launched magnetocentrifugally from the left face (red ring with orange centre). The jet propagates from left to right and follows a helical path as it succumbs to higher-order modes of the Kelvin-Helmholtz instability. Details in Ouyed, Clarke, & Pudritz.

 

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Line-of-sight integration of the magnetic energy density in a supersonic (M=10), super-Alfvénic turbulent medium using the Consistent Method of Characteristics (CMoC) in dzeus36 on a 256³ grid.

 

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Teaching resources

^*Course no longer part of the curriculum.

Official department curriculum

In 2007, the department curriculum was revised and fully documented. Expectations and outcomes for each course were defined, described, and placed on the web for faculty and student reference. I encourage students to review the course curriculum of each course they take, and to hold their professors accountable to its content.

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Research interests

I am the developer and curator of the widely used magnetohydrodynamics (MHD) computer code, ZEUS-3D. With it, I and my students perform multi-dimensional simulations of fluid phenomena such as astrophysical jets.

 

You can read more about my research interests here, consider graduate student projects here, and see a partial list of my publications here.

 

Research-related web sites

	ZEUS-3D website for gallery, description, user/installation guides, and downloading the code (version 3.5).
	AZEuS (AMR+ZEUS-3D) website for gallery and description. The code is not yet ready for distribution.
	EDITOR is my source-code manager for ZEUS-3D and AZEuS. Version 2.2 and user manual available for download.

 

Past and present students and PDFs: Where are they now?

 

I am pleased to say that every student who finished their degree with me moved on successfully to the next logical stage of their academic career.

Early in my career, I dabbled in radio astronomy using the VLA to observe radio galaxies such as 3C 219 (above left; image courtesy Alan Bridle, NRAO). You might imagine my surprise when, about ten years later, I happened upon our data immortalised in tile on the Hayden Planetarium floor (insert; image courtesy of Jodi)!

I am currently the department's Science Atlantic representative.

University Committees

National Committees/Panels

Software bar

Coming at some point, a table of possibly useful coding snippets...

DC's personal page

Despite my background in algorithm development and supercomputer simulations, I remain a bit of a ludite. I'm not a blogger, I don't do Facebook, and I most certainly don't tweet. I don't even own a cell phone! This web-page, such as it is, represents my first and likely only foray into "social media".

Background

Born in Charlottetown, Prince Edward Island to Sheila (née Davison; Charlottetown) and Alan Clarke (Halifax) in 1958, I was raised in Ontario and did my B.Sc. at Queen's University at Kingston (Honours Physics, 1981). My M.Sc. (Thesis: "Two-Dimensional Collapse of a Rotating Interstellar Cloud", 1984) was also from Queen's under Dick Henriksen. My Ph.D. (Dissertation: "A Search for the Effects of Active Magnetic Fields in Extragalactic Radio Sources", 1988) was from the University of New Mexico under Jack Burns and Mike Norman (LANL, NCSA).

I was a post-doctoral fellow at the NCSA (U. Illinois) from 1988–1992 under Mike Norman, and a post-doctoral research associate at the Harvard-Smithsonian CfA from 1992–1993 under Ramesh Narayan.

In 1993, I was appointed an assistant professor at Saint Mary's University, promoted to associate professor in 1995, gained tenure in 1996, and promoted again to full professor in 2003. During my 2000–2001 sabbatical leave, I was appointed astronome invité at l'observatoire de Grenoble. You can view my CV here.

Family

I went to the U.S. in 1984 single, came home in 1993 with a family. My wife now of 25 years, Jodi Asbell-Clarke, hails from North Haven, CT and is currently a senior science curriculum developer at a non-profit in Cambridge MA. My son, Dane, born in Albuquerque NM in 1989, is a graphic artist (check out his webpage!) in a small but growing firm in Halifax. My daughter, Alison, born in Urbana IL in 1992, is an undergraduate in political science at the University of Guelph.

I have one brother (Peter) who works and lives in Toronto. My mother lives in Halifax and my father and his wife Adaline live in Victoria.

Whimsy

I offer here a few snippets of "pre-historic" comedy, all from well before most of our students were born! They're timeless, they're clean, and they're fun; enjoy!

My favourite comic of all time, Dennis Wolfberg died in 1994 at the age of 48. If you have 27 minutes and can tolerate a few split sides, indulge yourself with these three You-Tube links.

Part 1: "His name was Marvin; I certainly learned that much! And his first name was More. More Marvin, more Marvin!" Part 2: "If we had a daughter, my wife wanted to name her Sue, which is a lovely name but for Jews is generally a verb!" Part 3: "...which is somewhat akin to telling someone in the path of a tidal wave: you might experience moisture!"

Many from my generation remember the Carol Burnett Show as a one-of-a-kind. In the few years SNL has been great, it has occasionally come close. A few of my favourite sketches include...

Harvey Korman trying not to laugh as Tim Conway fills himself with novacaine. "Stroke!...Stroke!...I think I'm having a...Stroke!" "Thank you, I saw it in the window, and I just couldn't resist it." (Part 1, Part 2)

And speaking of SNL, here are a few of my favourite characters. The only one from the "modern era" (Wiig's Gifford) doesn't seem to be on You-Tube yet.

Dana Carvey's Church Chat: "Well, isn't that special." Martin Short's Ed Grimley: "Gimme a break, I must say." Still searching for Kristen Wiig's Kathie Lee Gifford.

One of my Dad's all-time favourites was Victor Borge. His "phonetic punctuation" sketch is a classic.

"Phonetic Punctuation" "Hands Off" Victor Borge, the conductor

Quotable quotes

All the world's daft, save thee and me. And lately I've been wondering about thee.

If, in the last few years, you haven't discarded a major opinion or acquired a new one, check your pulse. You may be dead.

You don't really understand something until you can compute it.

Numquam ponenda est pluralitas sine necessitate; Plurality must never be posited without necessity.

The most incomprehensible thing about the Universe is that it is comprehensible.

Prediction is very difficult, especially about the future.

I cannot seriously believe in quantum theory because it cannot be reconciled with the idea that physics should represent a reality in time and space, free from spooky actions at a distance.

I have stated previously that the arrow of time should follow the arrow of universal expansion, and if the universe should start to collapse, we'd all start getting younger. I was wrong.

Nothing tastes as good as skinny feels.

And I find it kinda funny, I find it kinda sad; the dreams in which I'm dying are the best I've ever had; I find it hard to tell you, 'cause I find it hard to take; when people run in circles, it's a very very mad world, mad world.