Carbon capture and storage (CCS) is broadly recognised as having the potential to play a key role in meeting climate change targets, delivering low carbon heat and power, decarbonising industry and, more recently, its ability to facilitate the net removal of CO2 from the atmosphere. However, despite this broad consensus and its technical maturity, CCS has not yet been deployed on a scale commensurate with the ambitions articulated a decade ago. Thus, in this paper we review the current state-of-the-art of CO2 capture, transport, utilisation and storage from a multi-scale perspective, moving from the global to molecular scales. In light of the COP21 commitments to limit warming to less than 2 °C, we extend the remit of this study to include the key negative emissions technologies (NETs) of bioenergy with CCS (BECCS), and direct air capture (DAC). Cognisant of the non-technical barriers to deploying CCS, we reflect on recent experience from the UK's CCS commercialisation programme and consider the commercial and political barriers to the large-scale deployment of CCS. In all areas, we focus on identifying and clearly articulating the key research challenges that could usefully be addressed in the coming decade.

/pdf/carbon-capture-and-storage-ccs-the-way-forward-11rgsqyer0.pdf

Carbon capture and storage (CCS): the way forward

http://www.pvv.org/~stm/research/thermofluid.pdf

CO2 transport: Data and models – A review

While the wake of a circular cylinder and, to a lesser extent, the normal flat plate have been studied in considerable detail, the wakes of elliptic cylinders have not received similar attention. However, the wakes from the first two bodies have considerably different characteristics, in terms of three-dimensional transition modes, and near- and far-wake structure. This paper focuses on elliptic cylinders, which span these two disparate cases. The Strouhal number and drag coefficient variations with Reynolds number are documented for the two-dimensional shedding regime. There are considerable differences from the standard circular cylinder curve. The different three-dimensional transition modes are also examined using Floquet stability analysis based on computed two-dimensional periodic base flows. As the cylinder aspect ratio (major to minor axis) is decreased, mode A is no longer unstable for aspect ratios below 0.25, as the wake deviates further from the standard Benard–von Karman state. For still smaller aspect ratios, another three-dimensional quasi-periodic mode becomes unstable, leading to a different transition scenario. Interestingly, for the 0.25 aspect ratio case, mode A restabilises above a Reynolds number of approximately 125, allowing the wake to return to a two-dimensional state, at least in the near wake. For the flat plate, three-dimensional simulations show that the shift in the Strouhal number from the two-dimensional value is gradual with Reynolds number, unlike the situation for the circular cylinder wake once mode A shedding develops. Dynamic mode decomposition is used to characterise the spatially evolving character of the wake as it undergoes transition from the primary Benard–von Karman-like near wake into a two-layered wake, through to a secondary Benard–von Karman-like wake further downstream, which in turn develops an even longer wavelength unsteadiness. It is also used to examine the differences in the two- and three-dimensional near-wake state, showing the increasing distortion of the two-dimensional rollers as the Reynolds number is increased.

/pdf/low-reynolds-number-wakes-of-elliptical-cylinders-from-the-463b64cw63.pdf

Low-Reynolds-number wakes of elliptical cylinders: from the circular cylinder to the normal flat plate

Carbon capture and utilization (CCU) has attracted increased attention as a means to mitigate and adapt to climate change. CCU technology regards CO2 as a raw material and reduces CO2 emissions. Ho...

Carbon Capture and Utilization Technology without Carbon Dioxide Purification and Pressurization: A Review on Its Necessity and Available Technologies

Analysis and prediction of vortex-induced vibrations of variable-tension vertical risers in linearly sheared currents

Planar shear flow effects on particle dispersion over a normal flat plate

The present doctoral thesis concerns the wake dynamics from uniform and tapered bluff bodies. Bluff body configurations characterized by both arbitrary separation points and fixed separation points were considered, i.e. both the circular cylinder configuration and the normal flat plate configuration were used. Different flow regimes, from steady laminar wakes to transitional and turbulent wakes were explored. In all the cases, Direct Numerical Simulations were performed to solve the incompressible Navier-Stokes equations for an isothermal and Newtonian flow. Some results from the in-house PIV measurements were also presented. The characteristic features of the flow were investigated by means of frequency (both Fourier and Wavelet) analysis, three-dimensional flow visualizations and two-point correlations. Variations of the velocity and the pressure fields were also explored. The impact of the base pressure on the vortex formation process was elaborated. Reynolds-averaged statistical quantities were presented and the underlying flow physics were discussed.

https://brage.bibsys.no/xmlui/bitstream/11250/233375/1/124769_FULLTEXT01.pdf

Wake dynamics of flow past tapered bluff bodies

The distinction between d.type and k.type roughness on wall turbulence is well established [1] and related to the pitch-to-height ratio λ/k, where λ is the separation between roughness elements of height k. The results of the present study show that a k.type roughness with λ/k = 8 is turned into d.type roughness by the action of the Coriolis force due to imposed system rotation.

Roughness effects in a rotating turbulent channel

A non-planar mixing layer observed between parallel Couette flows by Narasimhamurthy et al. (Phys Rev E 85:036,302, 2012) is considered. Direct numerical simulation is chosen, and simulations are run in order to determine the critical Reynolds number at which the interface between the co-flowing laminar and non-laminar flow becomes unstable exhibiting a meandering motion. The necessary conditions required to trigger the shear-layer instability were also discussed. Different combinations of Reynolds numbers are chosen keeping the Reynolds number ratio between the laminar and non-laminar flows as constant. Preliminary results indicate that the onset of instability occurs, and a meandering motion is observed at the interface when Reynolds number for the non-laminar flow corresponds to 650.

Vagesh D. Narasimhamurthy

Papers

Planar shear flow effects on particle dispersion over a normal flat plate

Wake dynamics of flow past tapered bluff bodies

Roughness effects in a rotating turbulent channel

DNS of an Oscillating Shear Layer Between Two Parallel Couette Flows

Turbulent wake behind two intersecting flat plates